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  • AIP Publishing  (12)
  • 1
    Online Resource
    Online Resource
    Magnetic exchange induced Weyl state in a semimetal EuCd2Sb2
    AIP Publishing ; 2020
    In:  APL Materials Vol. 8, No. 1 ( 2020-01-01)
    Details
    In: APL Materials, AIP Publishing, Vol. 8, No. 1 ( 2020-01-01)
    Abstract: Magnetic Weyl semimetals (WSMs) bearing long-time seeking are still very rare. We have identified herein that EuCd2Sb2, a semimetal belonging to the type IV magnetic space group, hosts a magnetic exchange induced Weyl state via performing high magnetic field magnetotransport measurements and ab initio calculations. In the A-type antiferromagnetic structure, the external field larger than 3.2 T can align all Eu spins to be fully polarized along the c-axis and consequently drive EuCd2Sb2 into a spin polarized state. Magnetotransport measurements up to ∼55–60 T showed striking Shubnikov-de Hass oscillations associated with a nontrivial Berry phase. The ab initio calculations unveiled a phase transition of EuCd2Sb2 from a small gap antiferromagnetic topological insulator to a spin polarized WSM in which the Weyl points emerge along the Γ-Z path. Fermi arcs on (100) and (010) surfaces are also predicted. Meanwhile, the observed large anomalous Hall effect indicates the existence of Weyl points around the Fermi level. The results pave a way toward the realization of various topological states in a single material through the magnetic exchange manipulation.
    Type of Medium: Online Resource
    ISSN: 2166-532X
    URL: Article
    DOI: 10.1063/1.5129467
    Language: English
    Publisher: AIP Publishing
    Publication Date: 2020
    detail.hit.zdb_id: 2722985-3
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  • 2
    Online Resource
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    Influence of band bending and polarization on the valence band offset measured by x-ray photoelectron spectroscopy
    AIP Publishing ; 2010
    In:  Journal of Applied Physics Vol. 107, No. 10 ( 2010-05-15)
    Details
    In: Journal of Applied Physics, AIP Publishing, Vol. 107, No. 10 ( 2010-05-15)
    Abstract: The influence of band bending and polarization on the valence band offset measured by x-ray photoelectron spectroscopy (XPS) is discussed, and a modification method based on a modified self-consistent calculation is proposed to eliminate the influence and thus increasing the precision of XPS. Considering the spontaneous polarization at the surfaces and interfaces and the different positions of Fermi levels at the surfaces, we compare the energy band structures of Al/Ga-polar AlN/GaN and N-polar GaN/AlN heterojunctions, and give corrections to the XPS-measured valence band offsets. Other AlN/GaN heterojunctions and the piezoelectric polarization are also introduced and discussed in this paper.
    Type of Medium: Online Resource
    ISSN: 0021-8979 , 1089-7550
    URL: Article
    DOI: 10.1063/1.3408777
    Language: English
    Publisher: AIP Publishing
    Publication Date: 2010
    detail.hit.zdb_id: 220641-9
    detail.hit.zdb_id: 3112-4
    detail.hit.zdb_id: 1476463-5
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  • 3
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    On the drag reduction of an inclined wing via microstructures with the immersed boundary-lattice Boltzmann flux solver
    AIP Publishing ; 2023
    In:  Physics of Fluids Vol. 35, No. 8 ( 2023-08-01)
    Details
    In: Physics of Fluids, AIP Publishing, Vol. 35, No. 8 ( 2023-08-01)
    Abstract: Flow separation control has a wide application prospect in drag reduction for industry. This paper numerically studies the effect of microstructures on flow separation and drag reduction. Simple morphological microstructures, derived from the tilted shark scales, are attached to the wing at an angle of attack. The spacing and height of microstructures are made dimensionless by using the microstructure width and half of the wing width, respectively, that is, d̃m=dm/dAB and h̃m=hm/(H/2). The angle of attack is set to 10°. It is found that microstructures can reduce the motion amplitude of shed vortices, thereby suppressing flow separation and reducing drag. Both the planar and curved microstructures have excellent drag reduction performance. The microstructure spacing d̃m and tilt angle θ should not be too large or too small; otherwise, it will weaken the drag reduction ability. Cases d̃m=1.51, θ=20°, and θ=30° exhibit excellent drag reduction performance. The microstructure has the characteristic for being small, yet it needs to reach a certain height h̃m to effectively reduce drag. The case h̃m=0.667 is the most superior choice. Based on the proposed microstructure shape and spacing, the drag reduction performance of microstructures can reach more than 28%. Meanwhile, the drag reduction performance of microstructures increases with the improvement of the attachment proportion pm, and case pm≥50% is suggested for significant drag reduction performance. Finally, we discuss the drag reduction performance of microstructures on the wing at different angles of attack and find that microstructures can achieve good drag reduction, provided that the pressure drag caused by the flow separation is a significant proportion of the total drag and the flow separation occurs within the controllable range of microstructures.
    Type of Medium: Online Resource
    ISSN: 1070-6631 , 1089-7666
    URL: Article
    DOI: 10.1063/5.0159462
    Language: English
    Publisher: AIP Publishing
    Publication Date: 2023
    detail.hit.zdb_id: 1472743-2
    detail.hit.zdb_id: 241528-8
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  • 4
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    Multicomponent digital core construction and three-dimensional micro-pore structure characterization of shale
    AIP Publishing ; 2023
    In:  Physics of Fluids Vol. 35, No. 8 ( 2023-08-01)
    Details
    In: Physics of Fluids, AIP Publishing, Vol. 35, No. 8 ( 2023-08-01)
    Abstract: The components and pore structure of shale are complex due to the heterogeneous distribution of organic matter and the complex distributions of the minerals. The digital core, possessing the advantages of being economical and reusable, can be widely used to directly characterize the three dimensional (3D) micro-pore structure and to numerically simulate its physical properties. During construction of a digital shale core, it is a challenge to solve the multicomponent segmentation for the digital shale core, the contradiction between the sample size and image resolution, and the identification of the pore types in the 3D pore space. Therefore, an automatic workflow based on the gray gradient-maximum entropy-3D morphology was developed. The gray gradient-maximum entropy algorithm was used to segment each sub-image of focused ion beam scanning electron microscope images to generate segmented images. On this basis, the pore size distribution was optimized via 3D morphological erosion. Based on the concept of pore clusters, the organic and inorganic pores were identified using the 3D morphological method for the first time. The construction of a multicomponent digital shale core was realized. The 3D micro-pore structure of the organic and inorganic pores was characterized by pore connectivity, heterogeneity, and pore size distribution. The accuracy of the proposed method was verified using low-temperature N2 adsorption experiment data. The results of this study provide new insight into the multicomponent digital shale core construction and lay the foundation for the characterization of the petrophysical properties and micro-/nano-scale fluid flow simulations of shale.
    Type of Medium: Online Resource
    ISSN: 1070-6631 , 1089-7666
    URL: Article
    DOI: 10.1063/5.0155425
    Language: English
    Publisher: AIP Publishing
    Publication Date: 2023
    detail.hit.zdb_id: 1472743-2
    detail.hit.zdb_id: 241528-8
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  • 5
    Online Resource
    Online Resource
    Particle rotational trapping on a floating electrode by rotating induced-charge electroosmosis
    AIP Publishing ; 2016
    In:  Biomicrofluidics Vol. 10, No. 5 ( 2016-09-01)
    Details
    In: Biomicrofluidics, AIP Publishing, Vol. 10, No. 5 ( 2016-09-01)
    Abstract: We describe a novel rotating trait of induced-charge electroosmotic slip above a planar metal surface, a phenomenon termed “Rotating induced-charge electro-osmosis” (ROT-ICEO), in the context of a new microfluidic technology for tunable particle rotation or rotational trap. ROT-ICEO has a dynamic flow stagnation line (FSL) that rotates synchronously with a background circularly polarized electric field. We reveal that the rotating FSL of ROT-ICEO gives rise to a net hydrodynamic torque that is responsible for rotating fluids or particles in the direction of the applied rotating electric field either synchronously or asynchronously, the magnitude of which is adjusted by a balance between rotation of FSL and amplitude of angular-direction flow component oscillating at twice the field frequency. Supported by experimental observation, our physical demonstration with ROT-ICEO proves invaluable for the design of flexible electrokinetic framework in modern microfluidic system.
    Type of Medium: Online Resource
    ISSN: 1932-1058
    URL: Article
    DOI: 10.1063/1.4962804
    Language: English
    Publisher: AIP Publishing
    Publication Date: 2016
    detail.hit.zdb_id: 2265444-6
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  • 6
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    Online Resource
    An improved multiphase lattice Boltzmann flux solver with phase interface compression for incompressible multiphase flows
    AIP Publishing ; 2023
    In:  Physics of Fluids Vol. 35, No. 1 ( 2023-01-01)
    Details
    In: Physics of Fluids, AIP Publishing, Vol. 35, No. 1 ( 2023-01-01)
    Abstract: Numerical dissipation is ubiquitous in multiphase flow simulation. This paper introduces a phase interface compression term into the recently developed multiphase lattice Boltzmann flux solver and achieves an excellent interface maintenance. Here, the phase interface compression term only works in the interface region and is solved as the flux in finite volume discretization. At each cell interface, the interfacial compression velocity ur is determined by local reconstruction velocities of the multiphase lattice Boltzmann flux solver, which maintains the consistency of the flux evaluation. Meanwhile, the interfacial order parameter C in the phase interface compression term is obtained by the second order upwind scheme according to the interface normal direction. Numerical validation of the present model has been made by simulating the Zalesak problem, the single vortex problem, Rayleigh–Taylor instability, and bubble rising and coalescence. The obtained results indicate the validity and reliability of the present model.
    Type of Medium: Online Resource
    ISSN: 1070-6631 , 1089-7666
    URL: Article
    DOI: 10.1063/5.0131506
    Language: English
    Publisher: AIP Publishing
    Publication Date: 2023
    detail.hit.zdb_id: 1472743-2
    detail.hit.zdb_id: 241528-8
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  • 7
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    Online Resource
    Robust magnetoresistance in TaAs2 under pressure up to about 37 GPa
    AIP Publishing ; 2019
    In:  Applied Physics Letters Vol. 115, No. 12 ( 2019-09-16)
    Details
    In: Applied Physics Letters, AIP Publishing, Vol. 115, No. 12 ( 2019-09-16)
    Abstract: The extremely large magnetoresistance (XMR) in nonmagnetic semimetals has inspired growing interest owing to both intriguing physics and potential applications. We report the results of synchrotron X-ray diffraction and electrical transport measurements on TaAs2 under pressure up to ∼37 GPa, which revealed an anisotropic compression of the unit cell, formation of unusual As-As bonds above 9.5 GPa, and enhancement of metallicity. Interestingly, the MR of TaAs2 under pressure changed gently, which at 1.7 GPa is 96.6% and at 36.6 GPa is still 36.7%. The almost robust MR under pressure could be related to the nearly stable electronic structure unveiled by the ab initio calculations. The discovery would expand the potential use of XMR even under high pressure.
    Type of Medium: Online Resource
    ISSN: 0003-6951 , 1077-3118
    URL: Article
    DOI: 10.1063/1.5115008
    RVK:
    UA 1000
    Language: English
    Publisher: AIP Publishing
    Publication Date: 2019
    detail.hit.zdb_id: 211245-0
    detail.hit.zdb_id: 1469436-0
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  • 8
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    Online Resource
    Scattering due to Schottky barrier height spatial fluctuation on two dimensional electron gas in AlGaN/GaN high electron mobility transistors
    AIP Publishing ; 2013
    In:  Applied Physics Letters Vol. 103, No. 23 ( 2013-12-02)
    Details
    In: Applied Physics Letters, AIP Publishing, Vol. 103, No. 23 ( 2013-12-02)
    Abstract: A scattering mechanism related to the Schottky barrier height (SBH) spatial fluctuation of the two dimensional electron gas (2DEG) in AlGaN/GaN heterostructures is presented. We find that the low field mobility is on the order of 104–106 cm2/Vs. The 2DEG transport properties are found to be influenced by both the mobility and 2DEG density variations caused by the SBH fluctuation. Our results indicate that a uniform Schottky contact is highly desired to minimize the influence of SBH inhomogeneity on the device performance.
    Type of Medium: Online Resource
    ISSN: 0003-6951 , 1077-3118
    URL: Article
    DOI: 10.1063/1.4841715
    RVK:
    UA 1000
    Language: English
    Publisher: AIP Publishing
    Publication Date: 2013
    detail.hit.zdb_id: 211245-0
    detail.hit.zdb_id: 1469436-0
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  • 9
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    Online Resource
    Electrically insulating properties of the 5d double perovskite Sr2YOsO6
    AIP Publishing ; 2017
    In:  Journal of Applied Physics Vol. 122, No. 10 ( 2017-09-14)
    Details
    In: Journal of Applied Physics, AIP Publishing, Vol. 122, No. 10 ( 2017-09-14)
    Abstract: A high-pressure-synthesized double perovskite Sr2YOsO6 was investigated by synchrotron X-ray diffraction and measurements of its magnetic susceptibility, specific heat capacity, complex impedance, and complex dielectric constant. It crystallized into a monoclinic double perovskite structure (P21/n) with complete ordering of the Y and Os atoms. Its magnetic behaviors, including the antiferromagnetic transition temperature (∼52 K), Curie-Weiss effective moment [3.48(5) μB/Os], and Weiss temperature [−350.1(7) K] , were close to the respective values of Sr2YOsO6 previously synthesized without an applied pressure of 6 GPa. Transport property measurements revealed that the lower limit of the activation energy was 192(1) meV and the charge gap remained open regardless of the presence of magnetic order, conflicting with the electron delocalization predicted by theoretical calculations. Further consideration, including theoretical and experimental investigations of the roles of spin–orbit coupling and U of the 5d electrons of Os 5d-t2g3, may assist in understanding the general magnetic and insulating behaviors of quasi-half-filled 5d-t2g3oxides in the perovskite category toward the use of 5d double perovskite for magnetic applications.
    Type of Medium: Online Resource
    ISSN: 0021-8979 , 1089-7550
    URL: Article
    DOI: 10.1063/1.5001913
    Language: English
    Publisher: AIP Publishing
    Publication Date: 2017
    detail.hit.zdb_id: 220641-9
    detail.hit.zdb_id: 3112-4
    detail.hit.zdb_id: 1476463-5
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  • 10
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    Dislocation scattering in AlxGa1−xN∕GaN heterostructures
    AIP Publishing ; 2008
    In:  Applied Physics Letters Vol. 93, No. 18 ( 2008-11-03)
    Details
    In: Applied Physics Letters, AIP Publishing, Vol. 93, No. 18 ( 2008-11-03)
    Abstract: The theoretical electron mobility limited by dislocation scattering of a two-dimensional electron gas confined near the interface of AlxGa1−xN∕GaN heterostructures was calculated. Based on the model of treating dislocation as a charged line, an exponentially varied potential was adopted to calculate the mobility. The estimated mobility suggests that such a choice can simplify the calculation without introducing significant deviation from experimental data, and we obtained a good fitting between the calculated and experimental results. It was found that the measured mobility is dominated by interface roughness and dislocation scattering at low temperatures if dislocation density is relatively high ( & gt;109cm−2), and accounts for the nearly flattening-out behavior with increasing temperature.
    Type of Medium: Online Resource
    ISSN: 0003-6951 , 1077-3118
    URL: Article
    DOI: 10.1063/1.3013836
    RVK:
    UA 1000
    Language: English
    Publisher: AIP Publishing
    Publication Date: 2008
    detail.hit.zdb_id: 211245-0
    detail.hit.zdb_id: 1469436-0
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