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  • 1
    Publication Date: 2017-10-01
    Description: Magnetic skyrmions are topologically protected whirls that decay through singular magnetic configurations known as Bloch points. We used Lorentz transmission electron microscopy to infer the energetics associated with the topological decay of magnetic skyrmions far from equilibrium in the chiral magnet Fe 1– x Co x Si. We observed that the lifetime of the skyrmions depends exponentially on temperature, ~0 exp(EkBT) . The prefactor 0 of this Arrhenius law changes by more than 30 orders of magnitude for small changes of the magnetic field, reflecting a substantial reduction of the lifetime of skyrmions by entropic effects and, thus, an extreme case of enthalpy-entropy compensation. Such compensation effects, being well known across many different scientific disciplines, affect topological transitions and, thus, topological protection on an unprecedented level.
    Electronic ISSN: 2375-2548
    Topics: Natural Sciences in General
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 68 (1997), S. 1532-1535 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The design and performance of miniature ac susceptometers are described that are small enough to fit inside clamp type pressure cells. The susceptometers are comprised of a primary and a balanced pair of secondaries with numbers of turns as high as 1000 to optimize the coupling to the sample and hence measurement sensitivity. Two methods of balancing the vacuum signal of the secondaries are presented, making susceptibility measurements even in clamp cells generating large stray signals possible. With the technique presented here a comprehensive series of measurements was carried out into the pressure induced magnetic quantum phase transition of MnSi. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 68 (1997), S. 3120-3124 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We report on a compact loading cell for the continuous variation of uniaxial forces up to a few tons in low temperature investigations. The cell is based on a He activated bellow and a mechanical force amplification system. Due to its modular design, it may be used in studies of the effect of uniaxial pressure on solids or the in situ variation of hydrostatic pressure in an anvil cell. High pressure He is supplied by a fine capillary, so that bellow, force amplifier, and experiment may be cooled uniformly to mK temperatures even at high magnetic fields. The pressure in the bellow is controlled by a simple proportional-integral regulator at room temperature. Characteristic features of a piezoelectric sensor, used to measure the load at low temperature, are presented in detail. With the method described here, we observe long-term stability to better than ±0.2 N in sweeps over a wide range of temperatures and fields. The performance of the loading device is illustrated by means of measurements into the superconducting state of URu2Si2. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 67 (1996), S. 4023-4024 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We report on a method to avoid common mode related interferences by means of a voltage controlled current source. Our technique is discussed for the case of experimental investigations involving very low signal levels, as encountered in the study of small metallic samples, at very low temperatures. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A central question in the physics of interacting electron systems is whether conditions exist under which the conventional Landau description fails to describe the low energy excitations of the "normal'' metallic state. Measurements of the temperature and magnetic field dependences of the magnetization and resistivity—in particular of the de Haas–van Alphen and Shubnikov effects which provide sensitive probes of microscopic processes in metals—are currently being used to examine this question. Advances in material preparation and detection techniques have made it possible to conduct exhaustive studies in selected examples of systems of highly correlated d and f electrons. Most of our results will be shown to be consistent with the broad predictions of the Landau model. In some extreme circumstances, however, near low temperature transitions as a function of hydrostatic pressure or applied magnetic field, evidence has been collected which appears difficult to reconcile with the standard model of the metallic state.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 3369-3371 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have carried out in situ transient absorption and fluorescence spectroscopy measurements in two "wet''(OH content ∼0.1%) fused silica samples (Suprasil II from Heraeus Amersil and P-30 from Shin-Etsu Quartz Product) during KrF laser irradiation. Both samples exhibit an absorption peak at 210 nm corresponding to the E' center. For Suprasil II, there is also a 265 nm absorption peak, and both peaks increase with the number of irradiated pulses showing little relaxation after the laser was turned off. The region irradiated with three million pulses at 400 mJ/cm2 fluence ten months ago has a residual absorption of about 10%/cm at 210 nm. On the other hand, the P-30 shows a rapid increase in the 210 nm absorption in both the unirradiated and previously irradiated regions during the initial irradiation and levels off after a few thousand pulses. There is no residual absorption at the spot irradiated for 63 million pulses ten months ago. However, the initial rate of increase in the previously irradiated spot is twice as high as compared to the unirradiated spot. This suggests the density of the precursor state for the E' center is higher in the previously irradiated region. The fluorescence intensity at 650 nm increases with the induced absorption for Suprasil II, but is almost independent of the number of irradiation pulses in P-30. The quasilinear repetition-rate dependence suggests the fluorescence is transient in nature and relaxes partially between successive laser pulses.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 442 (2006), S. 797-801 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Since the 1950s, Heisenberg and others have addressed the problem of how to explain the appearance of countable particles in continuous fields. Stable localized field configurations were searched for an ingredient for a general field theory of elementary particles, but the majority of nonlinear ...
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [s.l.] : Macmillian Magazines Ltd.
    Nature 414 (2001), S. 427-430 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] A century of research on magnetic phenomena had led to the view that the normal state of itinerant-electron ferromagnets such as Fe, Ni and Co could be described in terms of the standard model of the metallic state or its extension known as the nearly ferromagnetic Fermi liquid theory. In ...
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  • 9
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] It has generally been believed that, within the context of the Bardeen–Cooper–Schrieffer (BCS) theory of superconductivity, the conduction electrons in a metal cannot be both ferromagnetically ordered and superconducting. Even when the superconductivity has been interpreted as ...
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Physica B: Physics of Condensed Matter 199-200 (1994), S. 634-636 
    ISSN: 0921-4526
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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