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Ding-sheng Wang ( 王鼎盛 ) (Institute of Physics, Beijing) dswang@aphy.iphy.ac +86-10-82649423

5. 　磁性与电子态 - Understanding/Predicting Magnetism from First Principles. Ding-sheng Wang ( 王鼎盛 ) (Institute of Physics, Beijing) dswang@aphy.iphy.ac.cn +86-10-82649423. 5. 　磁性与电子态. 5.0 引言 5.1 轨道 , 相互作用与自旋 5.2 原子和分子的磁矩 5.3 晶体的磁矩 5.4 晶体的磁各向异性 5.5 习题. 5. 　磁性与电子态.

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Ding-sheng Wang ( 王鼎盛 ) (Institute of Physics, Beijing) dswang@aphy.iphy.ac +86-10-82649423

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  1. 5.　磁性与电子态- Understanding/Predicting Magnetism from First Principles Ding-sheng Wang (王鼎盛)(Institute of Physics, Beijing)dswang@aphy.iphy.ac.cn +86-10-82649423

  2. 5.　磁性与电子态 5.0 引言5.1 轨道,相互作用与自旋5.2 原子和分子的磁矩5.3 晶体的磁矩5.4 晶体的磁各向异性5.5 习题

  3. 5.　磁性与电子态 5.0 引言5.1 轨道,相互作用与自旋5.2 原子和分子的磁矩5.3 晶体的磁矩5.4 晶体的磁各向异性5.5 习题

  4. Three Subjects in Magnetism Material structure V = { Zi, Ri } = {type, position} unit i = atom, atomic layer, crystal grain, ... Spin configuration M = { Mi } E = E({V, M}) = E({V, M}, {Hieff}, T, t…) 1. {Mi}: minimizing E({V, M}) at given {Hieff}, T, t … 2. Properties: P = P({V, M}) P = magnetic, optical, transport, ... 3. Electronic origin of E({V, M})

  5. Empirical Energy in Magnetism E({V,M}) = ENM(V) atomic structure + Si EMi (V,M) magnetization + Sij Jij(V,M) si.sj configuration + Sim K2im (V,M) (si.em)2 2nd anisotropy + Simn K4imn (V,M) (si.em)2 (si.en)24th anisotropy

  6. Energy Terms and Magnetic Properties < 0 0 > 0 ENM Structure Stable Unstable EMi Atomic moment Yes No Jij Configuration Ferro. Anti-ferro. Critical temp. High Low High K2im Anisotropy Uniaxial Soft Planar K4imn (when K2im =0)

  7. Energy Terms and Interaction ENM 1 eV Interatomic non-magnetic bonds EMi 100 meV Intraatomic exchange Jij 10 meV Interatomic exchange K2im -K4imn 1-0.001 meV Spin-orbit coupling and Challenge 1: After successes for explaining/predicting structure by ENM , how far can one go to describe the magnetism relevant interactions also from first principles ? Challenge 2: how the other properties of magnets can be explained/predicted also from first principles ?

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