Physics:Helimagnetism

From HandWiki
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. 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[1]) which have spiral modulation in addition to a permanent magnetic moment.

Helimagnetism was first proposed in 1959, as an explanation of the magnetic structure of manganese dioxide.[2] Initially applied to neutron diffraction, it has since been observed more directly by Lorentz electron microscopy.[3] Some helimagnetic structures are reported to be stable up to room temperature.[4] 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.[5]

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.[6] For these itinerant helimagnets, the direction of the helicity can be controlled by applied electric currents and magnetic fields.[7]

Helimagnetic materials
Material Temperature range Space group
β-MnO2[2][8] < 93 K P42/mnm
FeGe,[4] < 278 K P213
MnGe[9] < 170 K P213
MnSi,[10] < 29 K P213
FexCo1−xSi (0.3 ≤ x ≤ 0.85)[11][12] P213
Cu2OSeO3[13] < 58 K P213
FeP[6] < 120 K Pnma
FeAs[14] < 77 K Pnma
MnP[15] < 50 K Pnma
CrAs[16] < 261 K Pnma
Cr1/3NbS2[17][18] < 127 K P6322
Tb[19] 219–231 K P63/mmc
Dy[20] 85–179 K P63/mmc
Ho[21] 20–132 K P63/mmc

See also

References

  1. 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 (Elsevier BV) 507: 166843. doi:10.1016/j.jmmm.2020.166843. Bibcode2020JMMM..50766843P. 
  2. 2.0 2.1 Yoshimori, Akio (1959). "A New Type of Antiferromagnetic Structure in the Rutile Type Crystal". Journal of the Physical Society of Japan (Physical Society of Japan) 14 (6): 807–821. doi:10.1143/jpsj.14.807. Bibcode1959JPSJ...14..807Y. 
  3. Uchida, Masaya; Onose, Yoshinori; Matsui, Yoshio; Tokura, Yoshinori (2006). "Real-Space Observation of Helical Spin Order". Science (American Association for the Advancement of Science (AAAS)) 311 (5759): 359–361. doi:10.1126/science.1120639. PMID 16424334. Bibcode2006Sci...311..359U. 
  4. 4.0 4.1 Zhang, S. L.; Stasinopoulos, I.; Lancaster, T.; Xiao, F.; Bauer, A. et al. (2017). "Room-temperature helimagnetism in FeGe thin films". Scientific Reports (Springer Science and Business Media LLC) 7 (1): 123. doi:10.1038/s41598-017-00201-z. PMID 28273923. Bibcode2017NatSR...7..123Z. 
  5. Schoenherr, P.; Müller, J.; Köhler, L.; Rosch, A.; Kanazawa, N.; Tokura, Y.; Garst, M.; Meier, D. (2018). "Topological domain walls in helimagnets". Nature Physics (Springer Science and Business Media LLC) 14 (5): 465–468. doi:10.1038/s41567-018-0056-5. Bibcode2018NatPh..14..465S. 
  6. 6.0 6.1 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 (American Physical Society (APS)) 105 (13): 134424. doi:10.1103/physrevb.105.134424. ISSN 2469-9950. 
  7. 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 (Springer Science and Business Media LLC) 11 (1): 1601. doi:10.1038/s41467-020-15380-z. ISSN 2041-1723. 
  8. Regulski, M.; Przeniosło, R.; Sosnowska, I.; Hoffmann, J.-U. (2003-11-03). "Incommensurate magnetic structure of β−MnO2". Physical Review B (American Physical Society (APS)) 68 (17): 172401. doi:10.1103/physrevb.68.172401. ISSN 0163-1829. 
  9. 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". Physical Review B (American Physical Society (APS)) 99 (10): 100402(R). doi:10.1103/physrevb.99.100402. ISSN 2469-9950. Bibcode2019PhRvB..99j0402M. https://hal-cea.archives-ouvertes.fr/cea-02074769/file/2019_PRB-RC_MnGe%20MIEZE.pdf. 
  10. Stishov, Sergei M; Petrova, A E (2011-11-30). "Itinerant helimagnet MnSi". Physics-Uspekhi (Uspekhi Fizicheskikh Nauk (UFN) Journal) 54 (11): 1117–1130. doi:10.3367/ufne.0181.201111b.1157. Bibcode2011PhyU...54.1117S. 
  11. 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 (Physical Society of Japan) 54 (10): 3978–3986. doi:10.1143/jpsj.54.3978. Bibcode1985JPSJ...54.3978W. 
  12. 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. doi:10.1103/physrevb.95.144433. Bibcode2017PhRvB..95n4433B. http://resolver.tudelft.nl/uuid:3611a818-1a52-4be3-aa95-08ba3b78f25f. 
  13. Seki, S.; Yu, X. Z.; Ishiwata, S.; Tokura, Y. (2012). "Observation of Skyrmions in a Multiferroic Material". Science (American Association for the Advancement of Science (AAAS)) 336 (6078): 198–201. doi:10.1126/science.1214143. PMID 22499941. Bibcode2012Sci...336..198S. 
  14. Selte, Kari; Kjekshus, Arne; Andresen, Arne F.; Tricker, M. J.; Svensson, Sigfrid (1972). "Magnetic Structure and Properties of FeAs.". Acta Chemica Scandinavica (Danish Chemical Society) 26: 3101–3113. doi:10.3891/acta.chem.scand.26-3101. ISSN 0904-213X. 
  15. Forsyth, J B; Pickart, S J; Brown, P J (1966). "The structure of the metamagnetic phase of MnP". Proceedings of the Physical Society (IOP Publishing) 88 (2): 333–339. doi:10.1088/0370-1328/88/2/308. ISSN 0370-1328. 
  16. 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 (Danish Chemical Society) 25: 1703–1714. doi:10.3891/acta.chem.scand.25-1703. ISSN 0904-213X. 
  17. 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 (Physical Society of Japan) 52 (4): 1394–1401. doi:10.1143/jpsj.52.1394. ISSN 0031-9015. 
  18. 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 (American Physical Society (APS)) 91 (14): 144407. doi:10.1103/physrevb.91.144407. ISSN 1098-0121. 
  19. 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. 
  20. Herz, R.; Kronmüller, H. (1978). "Field-induced phase transitions in the helical state of dysprosium". Physica Status Solidi A (Wiley) 47 (2): 451–458. doi:10.1002/pssa.2210470215. Bibcode1978PSSAR..47..451H. 
  21. 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 (AIP Publishing) 69 (8): 5691–5693. doi:10.1063/1.347913. Bibcode1991JAP....69.5691T.