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翻訳と辞書　辞書検索 [ 開発暫定版 ] スポンサード リンク Quantum oscillations (experimental technique) ： ウィキペディア英語版 Quantum oscillations (experimental technique) In condensed matter physics, Quantum oscillations describes an experimental technique to map the Fermi surface of a metal in the presence of a strong magnetic field. The technique is based on the principle of Landau quantization of Fermions moving in a magnetic field. For a gas of free fermions in a strong magnetic field, the energy levels are quantized into bands, called the ''Landau levels'', whose separation is inversely proportional to the strength of the magnetic field. In a quantum oscillations experiment, the external magnetic field is varied, which causes the Landau levels to pass over the Fermi surface, which in turn results in oscillations of the Hall resistance.〔 Observation of quantum oscillations in a material is considered a signature of Fermi liquid behaviour. Quantum oscillations have been used to study high temperature superconducting materials such as cuprates and pnictides.〔 Studies using these experiments have shown that the ground state of underdoped cuprates behave similar to a Fermi liquid, and display characteristics such as Landau quasiparticles. ==Experiment== When a magnetic field is applied to a system of free Fermions, their energy states are quantized into the so-called Landau levels, given by $\backslash varepsilon\_l=\backslash frac\backslash left(\backslash ell\; +\backslash frac\backslash right)$ for integer-valued $\backslash ell$, where $B$ is the external magnetic field and $e,m^$ * are the fermion charge and effective mass respectively. When the external magnetic field $B$ is increased in an isolated system, the Landau levels expand, and eventually "fall off" the Fermi surface. This leads to oscillations in the observed energy of the highest occupied level, and hence in the Hall conductivity. The periodicity of these oscillations can be measured, and in turn can be used to determine the cross-sectional area of the Fermi surface. If the axis of the magnetic field is varied at constant magnitude, similar oscillations are observed. The oscillations occur whenever the Landau orbits touch the Fermi surface. In this way, the complete geometry of the Fermi sphere can be mapped.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Quantum oscillations (experimental technique)」の詳細全文を読む スポンサード リンク 翻訳と辞書 : 翻訳のためのインターネットリソース Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.