사용자:Aspere/번역장1

결정 내 서로 인접한 원자 간의 스핀 방향과 공간 배치가 서로 반대인, 교자성 배치의 예시.

교자성(altermagnetism)은 응집물질물리학에서 이상적인 결정에 존재하는 자기 상태 중 하나로,[1][2][3][4][5] 교자성 구조의 결정은 모두 동일선상에 있어 전체 자성은 0으로 상쇄된다.[1][5][6][7] 마찬가지로 전체 자성이 0이 되는 일반적인 동일선상의 반강자성과 달리, 교자성 내 전자 띠구조크라머르스 축퇴 상태에 있지 않고, 스핀에 의존하는 파수 벡터와 관련되어 있다.[1] 2024년 교자성과 관련된 실험 결과가 발표되었으며,[8][9] 스핀트로닉스 분야에서 응용할 수 있을 것으로 추정하고 있다.[6][10]

결정 구조 및 대칭 편집

교자성 물질 내 원자는, 원자의 스핀 방향과 공간 배치가 서로 교대하는 일정한 패턴을 보인다.[5][7]

Atoms with opposite magnetic moment are in altermagnets coupled by crystal rotation or mirror symmetry.[1][5][6][7][8][9] The spatial orientation of magnetic atoms may originate from the surrounding cages of non-magnetic atoms.[7][11] The opposite spin sublattices in altermagnetic manganese telluride (MnTe) are related by spin rotation combined with six-fold crystal rotation and half-unit cell translation.[7][8] In altermagnetic ruthenium dioxide (RuO2), the opposite spin sublattices are related by four-fold crystal rotation.[7][9]

 
교자성 물질인 텔루륨화 망간(MnTe, 왼쪽)과 이산화 루테늄(RuO2, 오른쪽)의 교차하는 자성 구조 및 결정 구조.

전기적 구조 편집

One of the distinctive features of altermagnets is a specifically spin-split band structure[7] which was first experimentally observed in work that was published in 2024.[8] Altermagnetic band structure breaks time-reversal symmetry,[7][11] Eks=E-ks (E is energy, k wavevector and s spin) as in ferromagnets, however unlike in ferromagnets, it does not generate net magnetization. The altermagnetic spin polarisation alternates in wavevector space and forms characteristic 2, 4, or 6 spin-degenerate nodes, respectively, which correspond to d-, g, or i-wave order parameters.[7] A d-wave altermagnet can be regarded as the magnetic counterpart of a d-wave superconductor.[12]

The altermagnetic spin polarization in band structure (energy–wavevector diagram) is collinear and does not break inversion symmetry.[7] The altermagnetic spin splitting is even in wavector, i.e. (kx2-ky2)sz.[7][8] It is thus also distinct from noncollinear Rasba or Dresselhaus spin texture which break inversion symmetry in noncentrosymmetric nonmagnetic or antiferromagnetic materials due to the spin-orbit coupling. Unconventional time-reversal symmetry breaking, giant ~1eV spin splitting and anomalous Hall effect was first theoretically predicted[11] and experimentally confirmed[13] in RuO2.

물질 편집

Direct experimental evidence of altermagnetic band structure in semiconducting MnTe and metallic RuO2 was first published in 2024.[8][9] Many more materials are predicted to be altermagnets – ranging from insulators, semiconductors, and metals to superconductors.[6][7] Altermagnetism was predicted in 3d and 2d materials[3][6] with both light as well as heavy elements and can be found in nonrelativistic as well as relativistic band structures.[7][8][11]

성질 편집

Altermagnets exhibit an unusual combination of ferromagnetic and antiferromagnetic properties, and remarkably more closely resemble those of ferromagnets.[1][5][6][7] Hallmarks of altermagnetic materials such as the anomalous Hall effect[11] have been observed before[13][14] (but this effect occurs also in other magnetically compensated systems such as non-collinear antiferromagnets[15]). Altermagnets also exhibit unique properties such as anomalous and spin currents that can change sign as the crystal rotates.[16]

각주 편집

  1. “Altermagnetism—A New Punch Line of Fundamental Magnetism”. 《Physical Review X》 (영어). 2022년 12월 8일. doi:10.1103/physrevx.12.040002. 2023년 12월 2일에 확인함. 
  2. Mazin, Igor (2024년 1월 8일). “Altermagnetism Then and Now”. 《Physics》 (영어) 17: 4. arXiv:2105.05820. doi:10.1103/PhysRevX.12.031042. 
  3. Mazin, Igor; González-Hernández, Rafael; Šmejkal, Libor (2023년 9월 5일), 《Induced Monolayer Altermagnetism in MnP(S,Se)$_3$ and FeSe》, arXiv:2309.02355, 2024년 2월 15일에 확인함 
  4. Wilkins, Alex (2024년 2월 14일). “The existence of a new kind of magnetism has been confirmed”. 《New Scientist》 (미국 영어). 2024년 2월 15일에 확인함. 
  5. Savitsky, Zack. “Researchers discover new kind of magnetism”. 《Science.org》. 2024년 2월 16일에 확인함. 
  6. Šmejkal, Libor; Sinova, Jairo; Jungwirth, Tomas (2022년 12월 8일). “Emerging Research Landscape of Altermagnetism”. 《Physical Review X》 12 (4): 040501. arXiv:2204.10844. Bibcode:2022PhRvX..12d0501S. doi:10.1103/PhysRevX.12.040501. 
  7. Šmejkal, Libor; Sinova, Jairo; Jungwirth, Tomas (2022년 9월 23일). “Altermagnetism: spin-momentum locked phase protected by non-relativistic symmetries”. 《Physical Review X》 12 (3): 031042. arXiv:2105.05820. doi:10.1103/PhysRevX.12.031042. ISSN 2160-3308. 
  8. Krempaský, J.; Šmejkal, L.; D’Souza, S. W.; Hajlaoui, M.; Springholz, G.; Uhlířová, K.; Alarab, F.; Constantinou, P. C.; Strocov, V.; Usanov, D.; Pudelko, W. R.; González-Hernández, R.; Birk Hellenes, A.; Jansa, Z.; Reichlová, H. (February 2024). “Altermagnetic lifting of Kramers spin degeneracy”. 《Nature》 (영어) 626 (7999): 517–522. arXiv:2308.10681. doi:10.1038/s41586-023-06907-7. ISSN 1476-4687. PMID 38356066. 
  9. Fedchenko, Olena; Minár, Jan; Akashdeep, Akashdeep; D’Souza, Sunil Wilfred; Vasilyev, Dmitry; Tkach, Olena; Odenbreit, Lukas; Nguyen, Quynh; Kutnyakhov, Dmytro; Wind, Nils; Wenthaus, Lukas; Scholz, Markus; Rossnagel, Kai; Hoesch, Moritz; Aeschlimann, Martin (2024년 2월 2일). “Observation of time-reversal symmetry breaking in the band structure of altermagnetic RuO 2”. 《Science Advances》 (영어) 10 (5): eadj4883. doi:10.1126/sciadv.adj4883. ISSN 2375-2548. PMC 10830110 |pmc= 값 확인 필요 (도움말). PMID 38295181. 
  10. “Altermagnetism proves its place on the magnetic family tree”. 《ScienceDaily》 (영어). 2024년 2월 15일에 확인함. 
  11. Šmejkal, Libor; González-Hernández, Rafael; Jungwirth, T.; Sinova, J. (2020년 6월 5일). “Crystal time-reversal symmetry breaking and spontaneous Hall effect in collinear antiferromagnets”. 《Science Advances》 6 (23). arXiv:1901.00445. doi:10.1126/sciadv.aaz8809. 
  12. Šmejkal, Libor; Sinova, Jairo; Jungwirth, Tomas (2022년 9월 23일). “Beyond Conventional Ferromagnetism and Antiferromagnetism: A Phase with Nonrelativistic Spin and Crystal Rotation Symmetry”. 《Physical Review X》 12 (3): 031042. arXiv:2105.05820. doi:10.1103/PhysRevX.12.031042. 
  13. Feng, Zexin; Zhou, Xiaorong; Šmejkal, Libor; Wu, Lei; Zhu, Zengwei; Guo, Huixin; González-Hernández, Rafael; Wang, Xiaoning; Yan, Han; Qin, Peixin; Zhang, Xin; Wu, Haojiang; Chen, Hongyu; Meng, Ziang; Liu, Li; Xia, Zhengcai; Sinova, Jairo; Jungwirth, Tomáš; Liu, Zhiqi (2022년 11월 7일). “An anomalous Hall effect in altermagnetic ruthenium dioxide”. 《Nature Electronics》 5 (11): 735–743. arXiv:2002.08712. doi:10.1038/s41928-022-00866-z. 
  14. Gonzalez Betancourt, R. D.; Zubáč, J.; Gonzalez-Hernandez, R.; Geishendorf, K.; Šobáň, Z.; Springholz, G.; Olejník, K.; Šmejkal, L.; Sinova, J.; Jungwirth, T.; Goennenwein, S. T. B.; Thomas, A.; Reichlová, H.; Železný, J.; Kriegner, D. (2023년 1월 20일). “Spontaneous Anomalous Hall Effect Arising from an Unconventional Compensated Magnetic Phase in a Semiconductor”. 《Physical Review Letters》 130 (3). arXiv:2112.06805. doi:10.1103/PhysRevLett.130.036702. 
  15. Nakatsuji, Satoru; Kiyohara, Naoki; Higo, Tomoya (November 2015). “Large anomalous Hall effect in a non-collinear antiferromagnet at room temperature”. 《Nature》 527 (7577): 212–215. doi:10.1038/nature15723. 
  16. Gonzalez Betancourt, R. D.; <C5><A0>mejkal, Libor; Vyborny, Karel; Yahagi, Yuta; Sinova, Jairo; Jungwirth, Tomas; Zelezny, Jakub (2021년 3월 26일). “Efficient Electrical Spin Splitter Based on Nonrelativistic Collinear Antiferromagnetism”. 《Physical Review Letters》 126: 127701. arXiv:2002.07073. doi:10.1103/PhysRevLett.126.127701.