Helimagnetism

Last updated
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.[ citation needed ] 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
MaterialTemperature rangeSpace group
β-MnO2 [2] [8] < 93 KP42/mnm
FeGe, [4] < 278 KP213
MnGe [9] < 170 KP213
MnSi, [10] < 29 KP213
FexCo1−xSi (0.3 ≤ x ≤ 0.85) [11] [12] P213
Cu2OSeO3 [13] < 58 KP213
FeP [6] < 120 KPnma
FeAs [14] < 77 KPnma
MnP [15] < 50 KPnma
CrAs [16] < 261 KPnma
FeCl3 [17] < 9 KR3
NiBr2 [18] < 22 KR3m
NiI2 [19] < 75 KR3m
Cr1/3NbS2 [20] [21] < 127 KP6322
Tb [22] 219–231 KP63/mmc
Dy [23] 85–179 KP63/mmc
Ho [24] 20–132 KP63/mmc

See also

Related Research Articles

Spintronics, also known as spin electronics, is the study of the intrinsic spin of the electron and its associated magnetic moment, in addition to its fundamental electronic charge, in solid-state devices. The field of spintronics concerns spin-charge coupling in metallic systems; the analogous effects in insulators fall into the field of multiferroics.

<span class="mw-page-title-main">Antiferromagnetism</span> Regular pattern of magnetic moment ordering

In materials that exhibit antiferromagnetism, the magnetic moments of atoms or molecules, usually related to the spins of electrons, align in a regular pattern with neighboring spins pointing in opposite directions. This is, like ferromagnetism and ferrimagnetism, a manifestation of ordered magnetism. The phenomenon of antiferromagnetism was first introduced by Lev Landau in 1933.

Magnetic semiconductors are semiconductor materials that exhibit both ferromagnetism and useful semiconductor properties. If implemented in devices, these materials could provide a new type of control of conduction. Whereas traditional electronics are based on control of charge carriers, practical magnetic semiconductors would also allow control of quantum spin state. This would theoretically provide near-total spin polarization, which is an important property for spintronics applications, e.g. spin transistors.

Multiferroics are defined as materials that exhibit more than one of the primary ferroic properties in the same phase:

Exchange bias or exchange anisotropy occurs in bilayers of magnetic materials where the hard magnetization behavior of an antiferromagnetic thin film causes a shift in the soft magnetization curve of a ferromagnetic film. The exchange bias phenomenon is of tremendous utility in magnetic recording, where it is used to pin the state of the readback heads of hard disk drives at exactly their point of maximum sensitivity; hence the term "bias."

<span class="mw-page-title-main">Spin ice</span>

A spin ice is a magnetic substance that does not have a single minimal-energy state. It has magnetic moments (i.e. "spin") as elementary degrees of freedom which are subject to frustrated interactions. By their nature, these interactions prevent the moments from exhibiting a periodic pattern in their orientation down to a temperature much below the energy scale set by the said interactions. Spin ices show low-temperature properties, residual entropy in particular, closely related to those of common crystalline water ice. The most prominent compounds with such properties are dysprosium titanate (Dy2Ti2O7) and holmium titanate (Ho2Ti2O7). The orientation of the magnetic moments in spin ice resembles the positional organization of hydrogen atoms (more accurately, ionized hydrogen, or protons) in conventional water ice (see figure 1).

Spin pumping is the dynamical generation of pure spin current by the coherent precession of magnetic moments, which can efficiently inject spin from a magnetic material into an adjacent non-magnetic material. The non-magnetic material usually hosts the spin Hall effect that can convert the injected spin current into a charge voltage easy to detect. A spin pumping experiment typically requires electromagnetic irradiation to induce magnetic resonance, which converts energy and angular momenta from electromagnetic waves to magnetic dynamics and then to electrons, enabling the electronic detection of electromagnetic waves. The device operation of spin pumping can be regarded as the spintronic analog of a battery.

Gallium manganese arsenide, chemical formula (Ga,Mn)As is a magnetic semiconductor. It is based on the world's second most commonly used semiconductor, gallium arsenide,, and readily compatible with existing semiconductor technologies. Differently from other dilute magnetic semiconductors, such as the majority of those based on II-VI semiconductors, it is not paramagnetic but ferromagnetic, and hence exhibits hysteretic magnetization behavior. This memory effect is of importance for the creation of persistent devices. In (Ga,Mn)As, the manganese atoms provide a magnetic moment, and each also acts as an acceptor, making it a p-type material. The presence of carriers allows the material to be used for spin-polarized currents. In contrast, many other ferromagnetic magnetic semiconductors are strongly insulating and so do not possess free carriers. (Ga,Mn)As is therefore a candidate as a spintronic material.

Ferromagnetic superconductors are materials that display intrinsic coexistence of ferromagnetism and superconductivity. They include UGe2, URhGe, and UCoGe. Evidence of ferromagnetic superconductivity was also reported for ZrZn2 in 2001, but later reports question these findings. These materials exhibit superconductivity in proximity to a magnetic quantum critical point.

<span class="mw-page-title-main">Magnetic structure</span>

The term magnetic structure of a material pertains to the ordered arrangement of magnetic spins, typically within an ordered crystallographic lattice. Its study is a branch of solid-state physics.

<span class="mw-page-title-main">Superexchange</span> Strong coupling between two cations through an intermediary anion

Superexchange or Kramers–Anderson superexchange interaction, is a prototypical indirect exchange coupling between neighboring magnetic moments by virtue of exchanging electrons through a non-magnetic anion known as the superexchange center. In this way, it differs from direct exchange, in which there is direct overlap of electron wave function from nearest neighboring cations not involving an intermediary anion or exchange center. While direct exchange can be either ferromagnetic or antiferromagnetic, the superexchange interaction is usually antiferromagnetic, preferring opposite alignment of the connected magnetic moments. Similar to the direct exchange, superexchange calls for the combined effect of Pauli exclusion principle and Coulomb's repulsion of the electrons. If the superexchange center and the magnetic moments it connects to are non-collinear, namely the atomic bonds are canted, the superexchange will be accompanied by the antisymmetric exchange known as the Dzyaloshinskii–Moriya interaction, which prefers orthogonal alignment of neighboring magnetic moments. In this situation, the symmetric and antisymmetric contributions compete with each other and can result in versatile magnetic spin textures such as magnetic skyrmions.

Mitsutaka Fujita was a Japanese physicist. He proposed the edge state that is unique to graphene zigzag edges. Also, he theoretically pointed out the importance and peculiarity of nanoscale and edge shape effects in nanographene. The theoretical concept of graphene nanoribbons was introduced by him and his research group to study the nanoscale effect of graphene. He was an associate professor at Tsukuba University, and died of a subarachnoid hemorrhage on March 18, 1998. His posthumous name is Rikakuin-Shinju-Houkou-Koji (理覚院深珠放光居士) in Japanese.

In magnetism, a nanomagnet is a nanoscopic scale system that presents spontaneous magnetic order (magnetization) at zero applied magnetic field (remanence).

In condensed matter physics, a quantum spin liquid is a phase of matter that can be formed by interacting quantum spins in certain magnetic materials. Quantum spin liquids (QSL) are generally characterized by their long-range quantum entanglement, fractionalized excitations, and absence of ordinary magnetic order.

Magnetic materials with strong spin-orbit interaction, such as: LaFeAsO, PrFe4P12, YbRu2Ge2, UO2, NpO2, Ce1−xLaxB6, URu2Si2 and many other compounds, are found to have magnetic ordering constituted by high rank multipoles, e.g. quadruple, octople, etc. Due to the strong spin-orbit coupling, multipoles are automatically introduced to the systems when the total angular momentum quantum number J is larger than 1/2. If those multipoles are coupled by some exchange mechanisms, those multipoles could tend to have some ordering as conventional spin 1/2 Heisenberg problem. Except the multipolar ordering, many hidden order phenomena are believed closely related to the multipolar interactions

An arsenide hydride or hydride arsenide is a chemical compound containing hydride (H−) and arsenide (As3−) ions in a single phase. They are in the class of mixed anion compounds.

Magnetic 2D materials or magnetic van der Waals materials are two-dimensional materials that display ordered magnetic properties such as antiferromagnetism or ferromagnetism. After the discovery of graphene in 2004, the family of 2D materials has grown rapidly. There have since been reports of several related materials, all except for magnetic materials. But since 2016 there have been numerous reports of 2D magnetic materials that can be exfoliated with ease just like graphene.

<span class="mw-page-title-main">Iron germanide</span> Chemical compound

Iron germanide (FeGe) is an intermetallic compound, a germanide of iron. At ambient conditions it crystallizes in three polymorphs with monoclinic, hexagonal and cubic structures. The cubic polymorph has no inversion center, it is therefore helical, with right-hand and left-handed chiralities.

<span class="mw-page-title-main">Manganese monosilicide</span> Chemical compound

Manganese monosilicide (MnSi) is an intermetallic compound, a silicide of manganese. It occurs in cosmic dust as the mineral brownleeite. MnSi has a cubic crystal lattice with no inversion center; therefore its crystal structure is helical, with right-hand and left-hand chiralities.

Mohindar Singh Seehra is an Indian-American Physicist, academic and researcher. He is Eberly Distinguished Professor Emeritus at West Virginia University (WVU).

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. Bibcode:2020JMMM..50766843P. doi: 10.1016/j.jmmm.2020.166843 . OSTI   1607351.
  2. 1 2 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. Bibcode:1959JPSJ...14..807Y. doi:10.1143/jpsj.14.807.
  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. Bibcode:2006Sci...311..359U. doi:10.1126/science.1120639. PMID   16424334. S2CID   37875453.
  4. 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. Springer Science and Business Media LLC. 7 (1): 123. Bibcode:2017NatSR...7..123Z. doi: 10.1038/s41598-017-00201-z . PMC   5427977 . PMID   28273923.
  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. arXiv: 1704.06288 . Bibcode:2018NatPh..14..465S. doi:10.1038/s41567-018-0056-5. S2CID   119021621.
  6. 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. American Physical Society (APS). 105 (13): 134424. arXiv: 2201.10358 . Bibcode:2022PhRvB.105m4424S. doi:10.1103/physrevb.105.134424. ISSN   2469-9950. S2CID   246276036.
  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. PMC   7105454 . PMID   32231211.
  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" (PDF). Physical Review B. American Physical Society (APS). 99 (10): 100402(R). Bibcode:2019PhRvB..99j0402M. doi:10.1103/physrevb.99.100402. ISSN   2469-9950. S2CID   128285958.
  10. ↑ Stishov, Sergei M; Petrova, A E (2011-11-30). "Itinerant helimagnet MnSi". Physics-Uspekhi. Uspekhi Fizicheskikh Nauk (UFN) Journal. 54 (11): 1117–1130. Bibcode:2011PhyU...54.1117S. doi:10.3367/ufne.0181.201111b.1157. S2CID   122357363.
  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. Bibcode:1985JPSJ...54.3978W. doi:10.1143/jpsj.54.3978.
  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. arXiv: 1701.05448 . Bibcode:2017PhRvB..95n4433B. doi:10.1103/physrevb.95.144433. S2CID   31673243.
  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. Bibcode:2012Sci...336..198S. doi:10.1126/science.1214143. PMID   22499941. S2CID   21013909.
  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. Bibcode:1966PPS....88..333F. 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. ↑ 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. Elsevier BV. 360: 1–5. doi:10.1016/j.jmmm.2014.01.051. ISSN   0304-8853.
  18. ↑ 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. Elsevier BV. 79 (4): 353–354. doi:10.1016/0375-9601(80)90369-2. ISSN   0375-9601.
  19. ↑ Kuindersma, S.R.; Sanchez, J.P.; Haas, C. (1981). "Magnetic and structural investigations on NiI2 and CoI2". Physica B+C. Elsevier BV. 111 (2–3): 231–248. doi:10.1016/0378-4363(81)90100-5. ISSN   0378-4363.
  20. ↑ 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. Bibcode:1983JPSJ...52.1394M. doi:10.1143/jpsj.52.1394. ISSN   0031-9015.
  21. ↑ 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. arXiv: 1501.03094 . Bibcode:2015PhRvB..91n4407B. doi:10.1103/physrevb.91.144407. ISSN   1098-0121. S2CID   117648270.
  22. ↑ 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.
  23. ↑ Herz, R.; Kronmüller, H. (1978). "Field-induced phase transitions in the helical state of dysprosium". Physica Status Solidi A. Wiley. 47 (2): 451–458. Bibcode:1978PSSAR..47..451H. doi:10.1002/pssa.2210470215.
  24. ↑ 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. Bibcode:1991JAP....69.5691T. doi:10.1063/1.347913.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.