Helimagnetism

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Lorentz TEM image of helical spin stripes in iron germanide (FeGe) at 90 K FeGe magnetic phase diagram2b.png
Lorentz TEM image of helical spin stripes in iron germanide (FeGe) at 90 K

Helimagnetism is a form of magnetic ordering where spins of neighbouring magnetic moments arrange themselves in a spiral or helical pattern, with a characteristic turn angle of somewhere between 0 and 180 degrees. It results from the competition between ferromagnetic and antiferromagnetic exchange interactions. [1] It is possible to view ferromagnetism and antiferromagnetism as helimagnetic structures with characteristic turn angles of 0 and 180 degrees respectively. Helimagnetic order breaks spatial inversion symmetry, as it can be either left-handed or right-handed in nature.

Strictly speaking, helimagnets have no permanent magnetic moment, and as such are sometimes considered a complicated type of antiferromagnet. This distinguishes helimagnets from conical magnets, (e.g. Holmium below 20 K [2] ) which have spiral modulation in addition to a permanent magnetic moment. Helimagnets can be characterized by the distance it takes for the spiral to complete one turn. In analogy to the pitch of screw thread, the period of repetition is known as the "pitch" of the helimagnet. If the spiral's period is some rational multiple of the crystal's unit cell, the structure is commensurate, like the structure originally proposed for MnO2. [3] On the other hand, if the multiple is irrational, the magnetism is incommensurate, like the updated MnO2 structure. [4]

Helimagnetism was first proposed in 1959, as an explanation of the magnetic structure of manganese dioxide. [3] Initially applied to neutron diffraction, it has since been observed more directly by Lorentz electron microscopy. [5] Some helimagnetic structures are reported to be stable up to room temperature. [6] Like how ordinary ferromagnets have domain walls that separate individual magnetic domains, helimagnets have their own classes of domain walls which are characterized by topological charge. [7]

Many helimagnets have a chiral cubic structure, such as the FeSi (B20) crystal structure type. In these materials, the combination of ferromagnetic exchange and the Dzyaloshinskii–Moriya interaction leads to helixes with relatively long periods. Since the crystal structure is noncentrosymetric even in the paramagnetic state, the magnetic transition to a helimagnetic state does not break inversion symmetry, and the direction of the spiral is locked to the crystal structure.

On the other hand, helimagnetism in other materials can also be based on frustrated magnetism or the RKKY interaction. The result is that centrosymmetric structures like the MnP-type (B31) compounds can also exhibit double-helix type helimagnetism where both left and right handed spirals coexist. [8] For these itinerant helimagnets, the direction of the helicity can be controlled by applied electric currents and magnetic fields. [9]

Helimagnetic materials
MaterialTemperature rangeSpace group
β-MnO2 [3] [4] < 93 KP42/mnm
FeGe, [6] < 278 KP213
MnGe [10] < 170 KP213
MnSi, [11] < 29 KP213
FexCo1−xSi (0.3 ≤ x ≤ 0.85) [12] [13] P213
Cu2OSeO3 [14] < 58 KP213
FeP [8] < 120 KPnma
FeAs [15] < 77 KPnma
MnP [16] < 50 KPnma
CrAs [17] < 261 KPnma
CrI2 [18] < 17 KCmc21
FeCl3 [19] < 9 KR3
NiBr2 [20] < 22 KR3m
NiI2 [21] < 75 KR3m
Cr1/3NbS2 [22] [23] < 127 KP6322
Tb [24] 219–231 KP63/mmc
Dy [25] 85–179 KP63/mmc
Ho [26] 20–132 KP63/mmc

See also

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References

  1. ↑ Blundell, Stephen, ed. (2001). Magnetism in condensed matter. Oxford master series in condensed matter physics. Oxford New York: Oxford University Press. pp. 99–100. ISBN   978-0-585-48360-3.
  2. ↑ Perreault, Christopher S.; Vohra, Yogesh K.; dos Santos, Antonio M.; Molaison, Jamie J. (2020). "Neutron diffraction study of magnetic ordering in high pressure phases of rare earth metal holmium". Journal of Magnetism and Magnetic Materials. 507. Elsevier BV: 166843. Bibcode:2020JMMM..50766843P. doi: 10.1016/j.jmmm.2020.166843 . OSTI   1607351.
  3. 1 2 3 Yoshimori, Akio (1959). "A New Type of Antiferromagnetic Structure in the Rutile Type Crystal". Journal of the Physical Society of Japan. 14 (6). Physical Society of Japan: 807–821. Bibcode:1959JPSJ...14..807Y. doi:10.1143/jpsj.14.807.
  4. 1 2 Regulski, M.; Przeniosło, R.; Sosnowska, I.; Hoffmann, J.-U. (2003-11-03). "Incommensurate magnetic structure of β−MnO2". Physical Review B. 68 (17). American Physical Society (APS): 172401. doi:10.1103/physrevb.68.172401. ISSN   0163-1829.
  5. ↑ Uchida, Masaya; Onose, Yoshinori; Matsui, Yoshio; Tokura, Yoshinori (2006). "Real-Space Observation of Helical Spin Order". Science. 311 (5759). American Association for the Advancement of Science (AAAS): 359–361. Bibcode:2006Sci...311..359U. doi:10.1126/science.1120639. PMID   16424334. S2CID   37875453.
  6. 1 2 Zhang, S. L.; Stasinopoulos, I.; Lancaster, T.; Xiao, F.; Bauer, A.; et al. (2017). "Room-temperature helimagnetism in FeGe thin films". Scientific Reports. 7 (1). Springer Science and Business Media LLC: 123. Bibcode:2017NatSR...7..123Z. doi: 10.1038/s41598-017-00201-z . PMC   5427977 . PMID   28273923.
  7. ↑ Schoenherr, P.; Müller, J.; Köhler, L.; Rosch, A.; Kanazawa, N.; Tokura, Y.; Garst, M.; Meier, D. (2018). "Topological domain walls in helimagnets". Nature Physics. 14 (5). Springer Science and Business Media LLC: 465–468. arXiv: 1704.06288 . Bibcode:2018NatPh..14..465S. doi:10.1038/s41567-018-0056-5. S2CID   119021621.
  8. 1 2 Sukhanov, A. S.; Tymoshenko, Y. V.; Kulbakov, A. A.; Cameron, A. S.; Kocsis, V.; et al. (2022-04-20). "Frustration model and spin excitations in the helimagnet FeP". Physical Review B. 105 (13). American Physical Society (APS): 134424. arXiv: 2201.10358 . Bibcode:2022PhRvB.105m4424S. doi:10.1103/physrevb.105.134424. ISSN   2469-9950. S2CID   246276036.
  9. ↑ Jiang, N.; Nii, Y.; Arisawa, H.; Saitoh, E.; Onose, Y. (2020-03-30). "Electric current control of spin helicity in an itinerant helimagnet". Nature Communications. 11 (1). Springer Science and Business Media LLC: 1601. doi: 10.1038/s41467-020-15380-z . ISSN   2041-1723. PMC   7105454 . PMID   32231211.
  10. ↑ Martin, N.; Mirebeau, I.; Franz, C.; Chaboussant, G.; Fomicheva, L. N.; Tsvyashchenko, A. V. (2019-03-13). "Partial ordering and phase elasticity in the MnGe short-period helimagnet" (PDF). Physical Review B. 99 (10). American Physical Society (APS): 100402(R). Bibcode:2019PhRvB..99j0402M. doi:10.1103/physrevb.99.100402. ISSN   2469-9950. S2CID   128285958.
  11. ↑ Stishov, Sergei M; Petrova, A E (2011-11-30). "Itinerant helimagnet MnSi". Physics-Uspekhi. 54 (11). Uspekhi Fizicheskikh Nauk (UFN) Journal: 1117–1130. Bibcode:2011PhyU...54.1117S. doi:10.3367/ufne.0181.201111b.1157. S2CID   122357363.
  12. ↑ Watanabe, Hideki; Tazuke, ichi; Nakajima, Haruo (1985). "Helical Spin Resonance and Magntization Measurement in Itinerant Helimagnet FexCo1−xSi (0.3≤x≤0.85)". Journal of the Physical Society of Japan. 54 (10). Physical Society of Japan: 3978–3986. Bibcode:1985JPSJ...54.3978W. doi:10.1143/jpsj.54.3978.
  13. ↑ Bannenberg, L. J.; Kakurai, K.; Falus, P.; Lelièvre-Berna, E.; Dalgliesh, R.; et al. (2017). "Universality of the helimagnetic transition in cubic chiral magnets: Small angle neutron scattering and neutron spin echo spectroscopy studies of FeCoSi". Physical Review B. 95 (14): 144433. arXiv: 1701.05448 . Bibcode:2017PhRvB..95n4433B. doi:10.1103/physrevb.95.144433. S2CID   31673243.
  14. ↑ Seki, S.; Yu, X. Z.; Ishiwata, S.; Tokura, Y. (2012). "Observation of Skyrmions in a Multiferroic Material". Science. 336 (6078). American Association for the Advancement of Science (AAAS): 198–201. Bibcode:2012Sci...336..198S. doi:10.1126/science.1214143. PMID   22499941. S2CID   21013909.
  15. ↑ Selte, Kari; Kjekshus, Arne; Andresen, Arne F.; Tricker, M. J.; Svensson, Sigfrid (1972). "Magnetic Structure and Properties of FeAs". Acta Chemica Scandinavica. 26. Danish Chemical Society: 3101–3113. doi: 10.3891/acta.chem.scand.26-3101 . ISSN   0904-213X.
  16. ↑ Forsyth, J B; Pickart, S J; Brown, P J (1966). "The structure of the metamagnetic phase of MnP". Proceedings of the Physical Society. 88 (2). IOP Publishing: 333–339. Bibcode:1966PPS....88..333F. doi:10.1088/0370-1328/88/2/308. ISSN   0370-1328.
  17. ↑ Selte, Kari; Kjekshus, Arne; Jamison, Warren E.; Andresen, Arne F.; Engebretsen, Jan E.; Ehrenberg, L. (1971). "Magnetic Structure and Properties of CrAs". Acta Chemica Scandinavica. 25. Danish Chemical Society: 1703–1714. doi: 10.3891/acta.chem.scand.25-1703 . ISSN   0904-213X.
  18. ↑ Schneeloch, John A.; Liu, Shunshun; Balachandran, Prasanna V.; Zhang, Qiang; Louca, Despina (2024-04-03). "Helimagnetism in the candidate ferroelectric CrI 2". Physical Review B. 109 (14): 144403. arXiv: 2310.12120 . doi:10.1103/PhysRevB.109.144403. ISSN   2469-9950.
  19. ↑ Kang, Byeongki; Kim, Changsoo; Jo, Euna; Kwon, Sangil; Lee, Soonchil (2014). "Magnetic state of FeCl 3 investigated by NMR". Journal of Magnetism and Magnetic Materials. 360. Elsevier BV: 1–5. doi:10.1016/j.jmmm.2014.01.051. ISSN   0304-8853.
  20. ↑ Adam, A; Billerey, D; Terrier, C; Katsumata, K; Magariño, J; Tuchendler, J (1980). "Magnetic resonance experiments in NiBr2 at high frequencies and high magnetic fields". Physics Letters A. 79 (4). Elsevier BV: 353–354. doi:10.1016/0375-9601(80)90369-2. ISSN   0375-9601.
  21. ↑ Kuindersma, S.R.; Sanchez, J.P.; Haas, C. (1981). "Magnetic and structural investigations on NiI2 and CoI2". Physica B+C. 111 (2–3). Elsevier BV: 231–248. doi:10.1016/0378-4363(81)90100-5. ISSN   0378-4363.
  22. ↑ Miyadai, Tomonao; Kikuchi, Katsuya; Kondo, Hiromitsu; Sakka, Shuzo; Arai, Masatoshi; Ishikawa, Yoshikazu (1983-04-15). "Magnetic Properties of Cr1/3NbS2". Journal of the Physical Society of Japan. 52 (4). Physical Society of Japan: 1394–1401. Bibcode:1983JPSJ...52.1394M. doi:10.1143/jpsj.52.1394. ISSN   0031-9015.
  23. ↑ Braam, D.; Gomez, C.; Tezok, S.; de Mello, E. V. L.; Li, L.; Mandrus, D.; Kee, Hae-Young; Sonier, J. E. (2015-04-07). "Magnetic properties of the helimagnet Cr1/3NbS2 observed byμSR". Physical Review B. 91 (14). American Physical Society (APS): 144407. arXiv: 1501.03094 . Bibcode:2015PhRvB..91n4407B. doi:10.1103/physrevb.91.144407. ISSN   1098-0121. S2CID   117648270.
  24. ↑ Palmer, S. B.; Baruchel, J.; Farrant, S.; Jones, D.; Schlenker, M. (1982). "Observation of Spiral Spin Antiferromagnetic Domains in Single Crystal Terbium". The Rare Earths in Modern Science and Technology. Boston, MA: Springer US. pp. 413–417. doi:10.1007/978-1-4613-3406-4_88. ISBN   978-1-4613-3408-8.
  25. ↑ Herz, R.; Kronmüller, H. (1978). "Field-induced phase transitions in the helical state of dysprosium". Physica Status Solidi A. 47 (2). Wiley: 451–458. Bibcode:1978PSSAR..47..451H. doi:10.1002/pssa.2210470215.
  26. ↑ Tindall, D. A.; Steinitz, M. O.; Kahrizi, M.; Noakes, D. R.; Ali, N. (1991). "Investigation of the helimagnetic phases of holmium in ac-axis magnetic field". Journal of Applied Physics. 69 (8). AIP Publishing: 5691–5693. Bibcode:1991JAP....69.5691T. doi:10.1063/1.347913.
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