Phase diagram of ultrathin ferromagnetic films with perpendicular
... Above T~, in the Ising nematic phase, no x derivatives u appear in the energy density, because thermal dislocations destroy even algebraic long-range order, and make the value of u have no meaning. Thus, the compression constant Kz becomes zero. This result also can be derived by the following argum ...
... Above T~, in the Ising nematic phase, no x derivatives u appear in the energy density, because thermal dislocations destroy even algebraic long-range order, and make the value of u have no meaning. Thus, the compression constant Kz becomes zero. This result also can be derived by the following argum ...
Electronic structure of Mn ions in „Ga,Mn…As - Paul-Drude
... Jahn-Teller effect manifests itself typically in anisotropic electronic paramagnetic resonances 共EPR’s兲 in the lowtemperature range, T⯝10–30 K, both in Cr-doped GaAs and in II-VI compounds.24,25 At slightly higher temperatures, the EPR spectrum exhibits isotropic behavior, due to the dynamic Jahn-Te ...
... Jahn-Teller effect manifests itself typically in anisotropic electronic paramagnetic resonances 共EPR’s兲 in the lowtemperature range, T⯝10–30 K, both in Cr-doped GaAs and in II-VI compounds.24,25 At slightly higher temperatures, the EPR spectrum exhibits isotropic behavior, due to the dynamic Jahn-Te ...
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... rotations generally make use of Rabi flopping. So far, qubit operations and toy model quantum computations have been performed by using different physical systems such as nuclear magnetic resonance, ion traps, and systems made of Josephson junctions [1-3]. In these qubit systems, the energy levels g ...
... rotations generally make use of Rabi flopping. So far, qubit operations and toy model quantum computations have been performed by using different physical systems such as nuclear magnetic resonance, ion traps, and systems made of Josephson junctions [1-3]. In these qubit systems, the energy levels g ...
Superconductivity
Superconductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic fields occurring in certain materials when cooled below a characteristic critical temperature. It was discovered by Dutch physicist Heike Kamerlingh Onnes on April 8, 1911 in Leiden. Like ferromagnetism and atomic spectral lines, superconductivity is a quantum mechanical phenomenon. It is characterized by the Meissner effect, the complete ejection of magnetic field lines from the interior of the superconductor as it transitions into the superconducting state. The occurrence of the Meissner effect indicates that superconductivity cannot be understood simply as the idealization of perfect conductivity in classical physics.The electrical resistivity of a metallic conductor decreases gradually as temperature is lowered. In ordinary conductors, such as copper or silver, this decrease is limited by impurities and other defects. Even near absolute zero, a real sample of a normal conductor shows some resistance. In a superconductor, the resistance drops abruptly to zero when the material is cooled below its critical temperature. An electric current flowing through a loop of superconducting wire can persist indefinitely with no power source.In 1986, it was discovered that some cuprate-perovskite ceramic materials have a critical temperature above 90 K (−183 °C). Such a high transition temperature is theoretically impossible for a conventional superconductor, leading the materials to be termed high-temperature superconductors. Liquid nitrogen boils at 77 K, and superconduction at higher temperatures than this facilitates many experiments and applications that are less practical at lower temperatures.