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The de Haas–van Alphen effect, often abbreviated to dHvA, is a quantum mechanical effect in which the magnetic moment of a pure metal crystal oscillates as the intensity of an applied magnetic field B is increased. Other quantities also oscillate, such as the resistivity (Shubnikov–de Haas effect), specific heat, and sound attenuation and speed.〔 〕〔 〕〔 〕 It was discovered in 1930 by Wander Johannes de Haas and his student Pieter M. van Alphen. The period, when plotted against , is inversely proportional to the area of the extremal orbit of the Fermi surface, in the direction of the applied field.〔 〕 : where S is the area of the Fermi surface normal to the direction of B. This effect is due to Landau quantization of electron energy in an applied magnetic field. A strong magnetic field — typically several teslas — and a low temperature are required to cause a material to exhibit the dHvA effect.〔 〕 In 1952, Lars Onsager explained the physics behind the effect, and, due to his interpretation, this effect can be used to image the Fermi surface of a metal, to measure the carrier density and more, which makes this a very powerful probing technique in condensed-matter physics. ==References== 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「De Haas–van Alphen effect」の詳細全文を読む スポンサード リンク
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