A model proposed by W. Heisenberg in his theory of magnetism to explain the mechanism behind the emergence of ferromagnetism based on quantum mechanical considerations. The part related to the exchange energy integral in the Coulomb interaction between electrons is summarized as 2 Js 1 s 2 as a function of the spin direction. Its magnitude is determined by the angle that the two spins s 1 and s 2 maintain relative to each other. J is a coefficient. It is mainly used in research on insulating magnetic materials. The Ising model, which is a simplified version of this, uses a vector that takes on only two values instead of spin. Source: Encyclopaedia Britannica Concise Encyclopedia About Encyclopaedia Britannica Concise Encyclopedia Information |
W.ハイゼンベルクが量子力学的考察をもとに強磁性出現のメカニズムを説明する磁性理論において提出した模型。電子間クーロン相互作用のなかの交換エネルギー積分に関する部分を,スピンの向きの関数として 2Js1・s2 の形にまとめたもの。その大きさは2つのスピン s1 ,s2 が互いにどのような角度を保っているかで決る。 J は係数。おもに絶縁性の磁性体の研究に用いられる。これを簡素化したイジング模型では,スピンの代りに2つの値しかとらないベクトルが使用されている。
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