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  • Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences  (52)
  • 1
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    Online Resource
    Effect of interface nucleation time of the GaN nucleation layer on the crystal quality of GaN film
    Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences ; 2015
    In:  Acta Physica Sinica Vol. 64, No. 12 ( 2015), p. 127305-
    Details
    In: Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 64, No. 12 ( 2015), p. 127305-
    Abstract: In this paper, the influences of the growth time of low-temperature (LT) GaN nucleation layer on the crystal quality and optical properties of GaN film are investigated. It is found that the optimal LT nucleation layer growth time can effectively reduce the crystal defects and is favorable to forming the annihilation of dislocations. GaN films are grown on c-plane sapphire substrates by metal-organic chemical vapor deposition. Crystal quality and optical properties are characterized by atomic force microscopy (AFM), scanning electron microscopy (SEM), high-resolution X-ray diffraction (HRXRD), and photoluminescence spectra, respectively. In the AFM images, the island density decreases as growth time increases, while the size of island becomes larger and the uniformity of island size deteriorates as growth time increases, leading to the phenomenon that the number of interfaces formed during the nucleation island coalescence, first decrease and then increase as detected by SEM, which also induces the screw dislocation density and edge dislocation density to first decrease and then increase as measured by HRXRD. This first-decrease-and-then-increase variation trend is consistent with the first-increase-and-then-decrease variation trend of the ratio of the band edge emission peak intensity to the yellow luminescence peak intensity tested by photoluminescence, which is confirmed by HRXRD. It is shown that GaN islands with different sizes and densities could lead to different mechanisms of dislocation evolution, thereby forming GaN epitaxial layers with different dislocation densities and optical properties. Through controlling the nucleation time, GaN films with the smallest dislocation density could be obtained.
    Type of Medium: Online Resource
    ISSN: 1000-3290 , 1000-3290
    URL: Journal
    URL: Article
    DOI: 10.7498/aps
    DOI: 10.7498/aps.64.127305
    Language: Unknown
    Publisher: Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences
    Publication Date: 2015
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  • 2
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    Experimental researches of laser phase lock with dual-servo feedbacks based on the piezoelectric transducer and fiber electrooptic phase modulator
    Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences ; 2016
    In:  Acta Physica Sinica Vol. 65, No. 23 ( 2016), p. 234204-
    Details
    In: Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 65, No. 23 ( 2016), p. 234204-
    Abstract: Fiber laser can be used for fiber optic communications,laser cutting,industrial manufacture,defense security and many other fields because of its advantages of narrow output linewidth,good reproducibility,etc.However,due to nonlinear and thermal effects,only a limited output power of a single fiber can be obtained with a sharp attenuation of the output beam quality,which obstructs the applications of fiber lasers.Therefore,the research of expanding the power of a fiber laser source while maintaining its beam quality by combining coherent beam has become a hot subject at present.In this field,the performance of phase control of coherent laser beams is a key factor to influence the efficiency of combination.The phase-controlling methods mainly include stochastic parallel gradient descent control algorithm, dithering,and heterodyne detection.In this paper,based on the active phase lock technology,the traditional heterodyne detection method is improved by the use of a fiber electro-optic phase modulator (EOM) rather than an acousto-optic frequency shifter (AOFS) to avoid the complex designs of the RF driver and circuit,which makes the overall experimental setup simple and stable.Moreover,in order to achieve a stable and wide correction range of phase locking,two servo paths are designed by use of piezoelectric transducer (PZT) and EOM1 to correct the optical phase differences.Firstly, a single-frequency narrow-width fiber laser with its central wavelength of 1531 nm is split by a beam splitter to generate a signal and a reference beam,respectively.The reference beam is phase modulated by another EOM2 with a 15 MHz signal.The phase error signal is obtained by demodulating the detected heterodyne signal at the modulation frequency. After that the error signal is divided into two parts,and sent to two PID servos to control PZT and EOM1,respectively. The PZT,used in the slow feedback loop,eliminates the laser phase error induced by the ambient temperature drift, while the EOM1,in the quick feedback loop,can eliminate the influence of high frequency noise.Two PID servos are carefully designed according to the measurements of the dynamic response of the PZT and EOM1.A stable feedback loop with a bandwidth of 220 kHz (limited by the bandwidth of PID controller) is obtained according to the measurement of its phase error signal spectrum,thus a tight lock is expected.As a consequence,the error of phase locking is less than 0.88°,which indicates that the phase control accuracy is λ/400.The long-term stability of the system is assessed by a 2 hour monitoring of the lock error signal.According to the analysis of Allan deviation,the best phase lock value of 0.006° can be obtained for an integration time of 160 s.The overall phase lock experimental setup is simple and easy to operate;moreover the phase lock can be further improved by optimizing the parameters of the PID controller.
    Type of Medium: Online Resource
    ISSN: 1000-3290 , 1000-3290
    URL: Journal
    URL: Article
    DOI: 10.7498/aps
    DOI: 10.7498/aps.65.234204
    Language: Unknown
    Publisher: Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences
    Publication Date: 2016
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  • 3
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    Double resonant sum-frequency generation in an external-cavity under high-efficiency frequency conversion
    Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences ; 2016
    In:  Acta Physica Sinica Vol. 65, No. 7 ( 2016), p. 074202-
    Details
    In: Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 65, No. 7 ( 2016), p. 074202-
    Abstract: In recent years, more than 90% of the signal laser power can be up-converted based on the high-efficiency double resonant external cavity sum-frequency generation (SFG), especially when the whole system runs under the undepleted pump approximation scheme. Therefore it is difficult to directly achieve an error signal with a high signal-to-noise ratio through the signal laser to lock its frequency to the cavity mode. In this paper a novel method, based on the frequency modulation of signal laser and demodulation of the SFG laser, is used to obtain the error signal to realize the cascade frequency locking between the two fundamental lasers and the external cavity. In this experiment, 1064 nm laser is the pump laser and 1583 nm laser is the signal laser. They are coupled into a ring cavity inside which a 5% MgO-doped PPLN (25 mm1 mm0.5 mm) is used to produce the SFG laser of 636 nm. When the pump laser is resonant with the external cavity, a circulating power of 14.3 W is obtained with its input power of 1.3 W. The reflectivity of the input coupling mirror of signal laser is 10% to restrain the impendence mismatch. The temperature of PPLN is set at 68.5 ℃ to reach the optimum SFG temperature. In order to keep the signal laser resonance inside the external cavity, one needs to lock its frequency to the cavity mode. A 28.5 kHz sinusoidal voltage is used to modulate the frequency of the signal laser so that the frequency of 636 nm laser is modulated simultaneously. Then 5% of the output 636 nm laser power is sent into a Si photodiode detector the signal of which is demodulated at the modulation frequency by a lock-in amplifier. Finally the demodulated signal is feedback to the frequency control port of signal laser. Under these conditions, 73% of 1583 nm signal laser power can be converted into 636 nm laser power when the incident power varies from 10 W to demodulation of the transmitted cavity mode of 1583 nm when the incident signal laser power is below 12 mW. When the signal laser power increases from 50 mW to 295 mW, the conversion efficiency linearly drops to 60%, which is mainly caused by depleting the 1064 nm pump laser power. Finally a 440 mW of 636 nm laser is generated with an incident signal laser power of 295 mW. This scheme can realize a high-efficiency SFG with a low input signal laser power or poor single-pass SFG efficiency.
    Type of Medium: Online Resource
    ISSN: 1000-3290 , 1000-3290
    URL: Journal
    URL: Article
    DOI: 10.7498/aps
    DOI: 10.7498/aps.65.074202
    Language: Unknown
    Publisher: Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences
    Publication Date: 2016
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  • 4
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    Research and data processing of double locked cavity ringdown absorption spectroscopy
    Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences ; 2016
    In:  Acta Physica Sinica Vol. 65, No. 12 ( 2016), p. 128701-
    Details
    In: Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 65, No. 12 ( 2016), p. 128701-
    Abstract: A continuous wave cavity ringdown spectroscopy based on a double-locking loop is proposed to improve the shortcoming of low acquisition rate of concentration in traditional scheme. A small portion of laser is separated to pass through a C2H2 reference cell, used to lock the laser frequency to the 1+3 band P(9)e absorption line of C2H2 at 6534.3634 cm-1 by the 1st harmonic demodulation of the frequency modulation spectroscopy. The remaining portion is incident on a high finesses cavity to observe the ringdown events. Meanwhile, the reflected light of cavity is used to extract the error signal to lock the laser based on the PDH frequency locking technique. As a consequence, the frequency drift of the laser and the jitter of the cavity length are improved, therefore a more relatively accuracy result is expected. The laser light is dual frequency modulated by a fiber coupled electro optic modulator (FEOM)in the above system. In order to optimize, to some extent, the asymmetry of the error signal caused by the residual amplitude modulation due to the inconsistency of the laser polarization direction with the extraordinary axis of the FEOM, the demodulation phase is adjusted carefully until the error signal is smoothed up and close to symmetry. Then, the effect of locking loop is examined. The frequency of laser, based on the measurement by a wavelength meter, is more stable and the relative frequency discrimination between the laser and the longitudinal mode of cavity is about 9.8 kHz. In addition, the PDH locking, ensuring the efficient coupling of the laser with the cavity, can gain a high acquisition rate of the concentration information. In order to obtain a complete ringdown event, the frequency of square wave to the fiber coupled acoustic optical modulator (FAOM) is limited to 30 kHz with the duty cycle of 85%, which is determined by the ringdown time and re-lock time. However, there exists a relatively large random noise in a series of ringdown time measurements of empty cavity, which is mainly caused by the errors of fitting and measurement. For the further improvement of the accuracy of experiment, an efficient digital filter, Kalman filter which can suppress the noise considerably at no expense of real-time capability, is used. The standard deviation of the ringdown time is reduced from 0.00333 to 0.00153. According to Allan variance analysis, the detection limit can reach 410-9 cm-1 for a 2 s integration time. Finally, the C2H2 gases with different concentrations from 100 ppb to 5 ppm are measured to demonstrate the linear response of this system.
    Type of Medium: Online Resource
    ISSN: 1000-3290 , 1000-3290
    URL: Journal
    URL: Article
    DOI: 10.7498/aps
    DOI: 10.7498/aps.65.128701
    Language: Unknown
    Publisher: Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences
    Publication Date: 2016
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  • 5
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    Measurement of jet evolution and electron energy spectrum during the process of laser-driven magnetic reconnection
    Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences ; 2015
    In:  Acta Physica Sinica Vol. 64, No. 16 ( 2015), p. 165201-
    Details
    In: Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 64, No. 16 ( 2015), p. 165201-
    Abstract: Magnetic reconnection (MR) is a universal physical process in plasma, in which the stored magnetic energy is converted into high-velocity flows and energetic particles. It is believed that MR plays an important role in many plasma phenomena such as solar fare, gamma-ray burst, fusion plasma instabilities, etc.. The process of MR has been studied in detail by dedicated magnetic-driven experiments. Here, we report the measurements of magnetic reconnection driven by Shenguang II lasers and Gekko XVII lasers. A collimated plasma jet is observed along the direction perpendicular to the reconnection plane with the optical probing. The present jet is very different from traditional magnetic reconnection outflows as known in the two-dimensional reconnection plane. In our experiment, by changing the delay of optical probing beam, we measure the temporal evolution of jet from 0.5 ns to 2.5 ns and its velocity around 400 km/s is deduced. Highcollimated jet is also confirmed by its strong X-ray radiation recorded by an X-ray pinhole camera. With the help of optical interferograms we calculate the jet configuration and its density distribution by using Abel inverting technique. A magnetic spectrometer with an energy range from hundred eV up to one MeV is installed in front of the jet, in the direction perpendicular to the reconnection plane, to measure the accelerated electrons. Two cases are considered for checking the acceleration of electrons. The results show that more accelerated electrons can be found in the reconnection case than in the case without reconnection. We propose that the formation and collimation of the plasma jet, and the electron energy spectrum may be possible directly influenced by the reconnection electric field, which is very important for understanding the energy conversion in the process of MR and establishment of the theoretical model. Finally the electron energy spectra of three different materials Al, Ta and Au are also shown in our work. The results indicate that the higher atomic number material can obtain a better signal-noise ratio, which provides some helpful references for our future work.
    Type of Medium: Online Resource
    ISSN: 1000-3290 , 1000-3290
    URL: Journal
    URL: Article
    DOI: 10.7498/aps
    DOI: 10.7498/aps.64.165201
    Language: Unknown
    Publisher: Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences
    Publication Date: 2015
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  • 6
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    Study on a novel probe for stimulated emission depletion Super-resolution Imaging of Mitochondria
    Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences ; 2020
    In:  Acta Physica Sinica Vol. 69, No. 16 ( 2020), p. 168702-
    Details
    In: Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 69, No. 16 ( 2020), p. 168702-
    Abstract: Optical microscopy has the advantages of real-time, non-invasive, tomography, three-dimensional imaging and living imaging. However, its spatial resolution cannot exceed half wavelength due to the existence of optical diffraction limit, which limits the development of optical microscopy. The primary task of super-resolution imaging is to break the diffraction limit and improve the resolution of optical microscopy for study of subcellular structure. Many kinds of super-resolution imaging technologies have been reported, among which the stimulated emission depletion (STED) microscopy is the earliest imaging technology to break the optical diffraction limit at present. STED microscopy can achieve nanometer-scale spatial resolution by breaking the optical diffraction limit with pure optical methods and a clever optical design. However, the application of STED microscopy in biomedicine, especially in live cell imaging is limited by high illumination power of STED light. In this paper, a new type of STED probe has been developed. The spectral analysis results show that the peak of the excitation and emission spectrum of this probe is as far as 122 nm away from each other, which is very suitable for the study of STED super-resolution because of its long stokes redshift. After colocalization with commercial mitochondrial dyes, it was found that the probe had a higher localization coefficient with commercial dyes and could be well positioned on mitochondrial organelles. At the same time, it was found that strong mitochondrial signal could be detected with low-power excitation light (only 1 μW in the experiment), and can get higher resolution of 62 nm under the STED light with 39.5 mW. The result of measuring the transverse resolution obtained by STED light under different power shows that the saturated light power of the probe is 3.5 mW (1.1 MW·cm〈sup〉–2〈/sup〉). Through the anti-bleaching testing, the probe still has a strong fluorescence intensity after more than 300 times of high power light irradiation, which indicates that the probe has a strong anti-bleaching property. Through a series of tests, this paper present a novel STED probe which has good mitochondrial targeting, excellent photobleaching-resistance, high resolution and low saturation power, which provides a new research tool for long-term live cell mitochondrial super-resolution imaging.
    Type of Medium: Online Resource
    ISSN: 1000-3290 , 1000-3290
    URL: Journal
    URL: Article
    DOI: 10.7498/aps
    DOI: 10.7498/aps.69.20200171
    Language: Unknown
    Publisher: Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences
    Publication Date: 2020
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  • 7
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    Highmobility AlGaN/GaN high electronic mobility transistors on GaN homo-substrates
    Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences ; 2018
    In:  Acta Physica Sinica Vol. 67, No. 7 ( 2018), p. 076801-
    Details
    In: Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 67, No. 7 ( 2018), p. 076801-
    Abstract: Gallium nitride (GaN) has great potential applications in high-power and high-frequency electrical devices due to its superior physical properties.High dislocation density of GaN grown on a foreign substrate leads to poor crystal quality and device reliability.The homo-epitaxial growth of GaN material has low dislocation density,which is the foundation of high performance of AlGaN/GaN highelectronic mobility transistor.However,it is difficult to prepare flat surface of GaN template or GaN substrate in thermal treatment process under the metal-organic chemical vapor deposition (MOCVD) ambient condition in which hydrogen (H2) is commonly used to clean the substrate surface,i.e.,to remove impurities from the substrate surface,since H2 would greatly enhance GaN decomposition in MOCVD high-temperature condition and etch GaN into roughness surfaceIn this work,an alternation gas model of ammonia/hydrogen (NH3/H2) mixed gas and H2 gas is designed.This technique is used in a thermal treatment process of GaN template and substrate by MOCVD.Then,we in-situ grow AlGaN/GaN HEMTs (high electron mobility transistors) on GaN template and GaN substrate,respectively.A series of alternation gas samples with various H2 treatment times is investigated.Optical microscope and atomic force microscope are used to observe the morphologies of GaN template and AlGaN/GaN HEMTs and two-dimensional electron gas (2DEG) mobility and density of AlGaN/GaN HEMTs are measured by contactless Hall measurement.Optical properties of AlGaN/GaN HEMTs are analyzed by photoluminescence at room temperature.The residual impurities of C and O in the GaN epilayer and the interfacial region between GaN epilayer and GaN substrate are analyzed by secondary ion mass spectrometry.The study results show that H2 enhances GaN decomposition in MOCVD at high temperature,and GaN decomposition greatly strengthens with H2 treatment time increasing leading to rough surface and the decrease of 2DEG mobility.The NH3/2 mixed gas could suppress GaN decomposition and avoid roughn surface,but go against cleaning out the purity from GaN surface,and the relativive intensity of the yellow band is higher.The NH3/2 mixed gas and 2 gas alternate thermal treatment model with proper 2 treatment time on GaN template or GaN substrate,not only obtains atomically flat surface of GaN template and HEMT structure,but also cleans out the purity from GaN surface,which is conducive to the increase of the electric properties of HEMT material.The highest 2DEG mobility reaches to 2136 cm2/V·s with 1 min 2 treatment in the alternate gas thermal treatment process grown on GaN templates and the electrical properties of HEMT material turn excellent.Finally,an alternate model with 5 min NH3/2 mixed gas followed by 1 min 2 and then 4 min mixed gas of thermal treatment process is used,the surface morphology of HEMT grown on GaN substrate shows highly uniform atomically steps and the root-mean-square value is 0.126 nm for 2 μm×2 μm scan area;the HEMT 2DEG mobility 2113 cm2/V·s grown on GaN substrate shows good electric properties,the residual impurities of C and O in the interfacial region between GaN epilayer and GaN substrates are below 1×1017 cm-3,showing clean interfacial.
    Type of Medium: Online Resource
    ISSN: 1000-3290 , 1000-3290
    URL: Journal
    URL: Article
    DOI: 10.7498/aps
    DOI: 10.7498/aps.67.20172581
    Language: Unknown
    Publisher: Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences
    Publication Date: 2018
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  • 8
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    Magnetic and electrical-thermal transport properties of Co〈sub〉3〈/sub〉Sn〈sub〉2〈/sub〉S〈sub〉2〈/sub〉 single crystal
    Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences ; 2023
    In:  Acta Physica Sinica Vol. 72, No. 17 ( 2023), p. 177102-
    Details
    In: Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 72, No. 17 ( 2023), p. 177102-
    Abstract: Co〈sub〉3〈/sub〉Sn〈sub〉2〈/sub〉S〈sub〉2〈/sub〉 is a magnetic Weyl semimetal with special magnetic and electronic structure. Its unique band structure makes it have many interesting physical properties such as abnormal Hall effect, negative magnetoresistance effect, and abnormal Nernst effect. In this work, high quality Co〈sub〉3〈/sub〉Sn〈sub〉2〈/sub〉S〈sub〉2〈/sub〉 single crystal with a dimension of 8 mm×7 mm×0.5 mm is synthesized by self-flux method. We measure its electrical transport properties (magnetoresistance effect, Hall effect, etc.) and thermal transport properties (Seebeck effect) at low temperature. The free surface of the single crystal exhibits obvious layered growth characteristics, indicating that the Co〈sub〉3〈/sub〉Sn〈sub〉2〈/sub〉S〈sub〉2〈/sub〉 crystal grows along the 〈i〉c〈/i〉-axis direction. The value of the normalized resistivity 〈i〉ρ〈/i〉〈sub〉3 K〈/sub〉/〈i〉ρ〈/i〉〈sub〉300 K〈/sub〉 for the single crystal sample at 3 K is only 0.08, indicating that the crystal quality of the sample is at a relatively high level. The thermomagnetic (〈i〉M〈/i〉-〈i〉T〈/i〉) curves show that a special magnetic structure near 140 K (〈i〉T〈/i〉〈sub〉A〈/sub〉) below the Curie temperature point (〈i〉T〈/i〉〈sub〉C〈/sub〉 = 178 K). This special magnetic structure is a magnetic transition state in which ferromagnetic state and antiferromagnetic state coexist, making them appear as a local minimum point in the 〈i〉M〈/i〉-〈i〉T〈/i〉 curve. The Co〈sub〉3〈/sub〉Sn〈sub〉2〈/sub〉S〈sub〉2〈/sub〉 shows a negative anomalous “convex” magnetoresistance in a large range of 100—160 K, and there exists a maximum critical magnetic field 〈i〉B〈/i〉〈sub〉0〈/sub〉 (1.41 T), near 〈i〉T〈/i〉〈sub〉A〈/sub〉. The coercivity 〈i〉H〈/i〉〈sub〉C〈/sub〉 drops to almost zero at 〈i〉T〈/i〉〈sub〉A〈/sub〉 and the Hall resistivity 〈i〉ρ〈/i〉〈sub〉〈i〉yx〈/i〉〈/sub〉 also reaches a maximum value of about 20 μΩ·cm. This may be due to the competition between ferromagnetic state and antiferromagnetic state to form non-trivial spin texture, resulting in the unique electrical transport behavior near 〈i〉T〈/i〉〈sub〉A〈/sub〉. When the temperature rises to 〈i〉T〈/i〉〈sub〉C〈/sub〉, the Co〈sub〉3〈/sub〉Sn〈sub〉2〈/sub〉S〈sub〉2〈/sub〉 undergoes a ferromagnetic phase transition, with a saturation magnetization of 〈i〉M〈/i〉〈sub〉S,〈/sub〉 anomalous Hall conductivity 〈inline-formula〉〈tex-math id="M1"〉\begin{document}$ {\sigma }_{yx}^{\rm A} $\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="17-20230621_M1.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="17-20230621_M1.png"/〉〈/alternatives〉〈/inline-formula〉, and Hall resistivity 〈i〉ρ〈/i〉〈i〉〈sub〉yx〈/sub〉〈/i〉 sharply decreasing. Large anomalous Hall conductance 〈inline-formula〉〈tex-math id="M2"〉\begin{document}$ {\sigma }_{yx}^{A} $\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="17-20230621_M2.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="17-20230621_M2.png"/〉〈/alternatives〉〈/inline-formula〉 and anomalous Hall angle 〈inline-formula〉〈tex-math id="M3"〉\begin{document}$ {\sigma }_{yx}^{\rm A}/\sigma $\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="17-20230621_M3.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="17-20230621_M3.png"/〉〈/alternatives〉〈/inline-formula〉 are also present in Co〈sub〉3〈/sub〉Sn〈sub〉2〈/sub〉S〈sub〉2〈/sub〉, with these values reaching 1.4×10〈sup〉3〈/sup〉 Ω〈sup〉−1〈/sup〉·cm〈sup〉−1〈/sup〉 and 18%, respectively. The magnetoresistance measurements reveal that the variation of the magnetoresistance with the magnetic field is due to the combination of linear and parabolic contributions. The change in magnetoresistance with the angle 〈i〉θ〈/i〉 between the magnetic field 〈i〉B〈/i〉 and the current 〈i〉I〈/i〉 has a reversal symmetry with C〈sub〉2〈i〉x〈/i〉〈/sub〉 symmetry, and the change in 〈i〉θ〈/i〉 does not affect the contribution of its magnetoresistance source. In addition, positive magnetoresistance and negative magnetoresistance are found to be shifted at about 60 K. the shift in positive magnetoresistance and negative magnetoresistance are mainly attributed to the competing positive contribution of the Lorentz force to the magnetoresistance and the negative contribution of the spin disorder. The scattering mechanism of Co〈sub〉3〈/sub〉Sn〈sub〉2〈/sub〉S〈sub〉2〈/sub〉 at low temperature is a combination of acoustic wave scattering and electron– phonon scattering. At 60–140 K, the enhancement of spin disorder causes enhanced electron–phonon scattering, resulting in a plateau characteristic of the Seebeck coefficient 〈i〉S〈/i〉. The research shows that the special magnetic structure and electron spin of Co〈sub〉3〈/sub〉Sn〈sub〉2〈/sub〉S〈sub〉2〈/sub〉 at low temperatures have an important influence on its electrothermal transport behavior.
    Type of Medium: Online Resource
    ISSN: 1000-3290 , 1000-3290
    URL: Article
    DOI: 10.7498/aps.72.20230621
    Language: Unknown
    Publisher: Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences
    Publication Date: 2023
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  • 9
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    New advances in the research of stimulated emission depletion super-resolution microscopy
    Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences ; 2020
    In:  Acta Physica Sinica Vol. 69, No. 10 ( 2020), p. 108702-
    Details
    In: Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 69, No. 10 ( 2020), p. 108702-
    Abstract: Due to the influence of the diffraction limit, the lateral spatial resolution and axial spatial resolution of traditional optical microscopes are limited to ~200 nm and ~500 nm, respectively. In the past two decades, with the rapid development of high-intensity lasers, high-sensitivity detectors and other optoelectronic devices, there have been reported many super-resolution imaging techniques that bypass the optical diffraction limit with different methods. Among these techniques, stimulated emission depletion microscopy (STED) technology has the advantages of high imaging resolution and fast imaging speed. This technology uses two lasers for imaging, one of which is used to excite fluorescence, and the other donut-shaped depletion laser is used to suppress the emission of fluorescent molecules around the fluorescent spot, in order to reduce the fluorescence point spread function and achieve super resolution Imaging. After recent years of development, the STED system has got great progress no matter from the generation, calibration and scanning of the beam, and the final imaging. In terms of laser source, new laser sources such as continuous wave beams, supercontinuum laser, stimulated Raman scattered laser, and higher-order Bessel beams have appeared; in scanning and calibration, new efficiency technology such as parallel scanning and automatic calibration have also appeared; In imaging, new methods such as time gating and phasor analysis have emerged to improve imaging quality. These new technologies and methods are of great significance to improve the efficiency of STED system construction and imaging. In addition, this paper also focuses on the ways to expand the imaging functions of the STED system. First, for three-dimensional STED imaging, this paper mainly introduces three methods to realize three-dimensional STED imaging by wavefront non-coherent adjustment, 4Pi and structured light illumination methods. Second, for multi-color imaging, this paper introduces several dual-color and multi-color imaging techniques for special dyes. Third, this paper introduces the combination of STED technology with fluorescence correlation spectroscopy technology, cell expansion technology, scanning ion-conductance microscope, photo-activated localization microscopy/stochastic optical reconstruction microscopy and other technologies. Finally, this paper systematically discusses the new research progress of STED technology in recent years, and discusses the future development trend of STED technology.
    Type of Medium: Online Resource
    ISSN: 1000-3290 , 1000-3290
    URL: Journal
    URL: Article
    DOI: 10.7498/aps
    DOI: 10.7498/aps.69.20200168
    Language: Unknown
    Publisher: Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences
    Publication Date: 2020
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  • 10
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    Avalanche effect in plasma under high-power microwave irradiation
    Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences ; 2017
    In:  Acta Physica Sinica Vol. 66, No. 19 ( 2017), p. 195202-
    Details
    In: Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 66, No. 19 ( 2017), p. 195202-
    Abstract: High-power microwave (HPM) weapon, which is destructive to electronic systems, has developed rapidly due to the great progress of HPM devices and technologies. Plasma with distinctive electromagnetic characteristics is under advisement as one of potentially effective protection materials. Therefore, research on avalanche ionization effect in plasma caused by the interaction between HPM and plasma is of significance for its HPM protection performance. Based on the method of fluid approximation, the wave equation, the electron drift diffusion equation and the heavy species transport equation, explaining the propagation of microwave and the change of the charged particles inside plasma, are established to study the avalanche ionization effect under the HPM radiation. A two-dimensional physical model is built with the help of software COMSOL according to the plasma protection array designed to disturb the propagation of the HPM pulses. It can be shown that the emergence of avalanche effect is greatly affected by the incident power of microwave, and the generation time would be influenced by the initial electron density. Moreover, it can be observed that the avalanche effect appears only when the plasma array is irradiated for a period of time, which means that the performance of HPM is presented as gathering effect, and a large amount of energy is needed to change the internal particle balance in plasma. In addition, the electron density inside the plasma changes rapidly and complicatedly while the avalanche effect comes into being. Besides, the cutoff frequency of the plasma exceeds the frequency of the incident wave with the increase of electron density, which leads to that the electromagnetic wave cannot propagate in the plasma, so that the plasma can be used to protect the HPM irradiation.
    Type of Medium: Online Resource
    ISSN: 1000-3290 , 1000-3290
    URL: Journal
    URL: Article
    DOI: 10.7498/aps
    DOI: 10.7498/aps.66.195202
    Language: Unknown
    Publisher: Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences
    Publication Date: 2017
    Location Call Number Limitation Availability
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