Skyrmion lattice in the doped semiconductorFe1−xCoxSi

Abstract

We report a comprehensive small angle neutron scattering study (SANS) of the magnetic phase diagram of the doped semiconductor Fe1−xCoxSi for x = 0.2 and 0.25. For magnetic field parallel to the neutron beam we observe a six-fold intensity pattern under field-cooling, which identifies the A-phase of Fe1−xCoxSi as a skyrmion lattice. The regime of the skyrmion lattice is highly hysteretic and extents over a wide temperature range, consistent with the site disorder of the Fe and Co atoms. Our study identifies Fe1−xCoxSi is a second material after MnSi in which a skyrmion lattice forms and establishes that skyrmion lattices may also occur in strongly doped semiconductors.PACS numbers: 72.80. Ga, Recently a skyrmion lattice was identified in the cubic B20 system MnSi [1,2], that is, magnetic order representing a crystallization of topologically stable, particle-like knots of the spin structure originally anticipated to occur in anisotropic materials [3]. This raises the question for further magnetic materials with skyrmion lattices and if they are a general phenomenon in cubic magnets without inversion symmetry as suggested by our theoretical treatment in [1]. Because MnSi is a pure metal, an additional question concerns if skyrmion lattices are sensitive to disorder and whether they also exist in semiconductors and insulators. More generally, the microscopic identification of a skyrmion lattice in MnSi represents also a showcase for similar lattice structures considered in nuclear physics [4,5], quantum Hall systems [6,7], and liquid crystals [8].

Phase diagram of the Dzyaloshinskii-Moriya helimagnet Ba2CuGe2O7in canted magnetic fields

“…1, panel (b): For the propagation vector q along (1,1,0), spins are confined in (1,-1,0) plane, the rotation angle β relative to a perfect antiparallel alignment is 9.7 • per unit cell. Due to the equivalency of the (1,±1,0) directions, two equally Cu (1) Cu (2) Cu (3) D z (1,2) D z (2,3) D y (2,3) D y (1,2) (a) (c) The angle enclosed by the (1,1,0) direction and the propagation vector q is denoted φ, similar to the notation used in Refs. [18,19].…”

“…Recently, helical magnetic spin-structures have regained lots of interest, partially motivated by the discovery of topologically stable skyrmion phases in cubic MnSi and other B20 compounds [1][2][3][4][5]. Also the potential multiferroic properties of helimagnets have been recognized in recent years.…”

Double-kphase of the Dzyaloshinskii-Moriya helimagnet Ba2CuGe2OMühlbauer1, Gvasaliya2, Pomjakushina3 et al. 2011Phys. Rev. BSelf Cite235421View full textAdd to dashboardCite

“…Dzyaloshinskii-Moriya (DM) antisymmetric exchange interactions [1,2] and their role in incommensurate magnetic structures are once again at the forefront of condensed matter research. One reason for the renewed interest is the discovery of novel topological skyrmion phases in the DM helimagnet MnSi and related compounds [3,4]. The other is the role that DM interactions play in certain scenarios of the multiferroic effect [5,6].…”

Incommensurate Magnetic Structure in the Cubic Noncentrosymmetric Ternary Compound Pr5Ru3Al2

“…Instead, magnetic ordering was observed in the DC magnetic susceptibility at T N ≃ 3.8 K. Neutron powder diffraction further indicates that an incommensurate magnetic structure is established below T N , with the magnetic modulation vector q ≃ (0.066, 0.066, 0.066) (r.l.u.). A candidate for the magnetic structure is proposed using the representation analysis.Non-colinear incommensurate magnetic structures, such as a helical magnetic structure, have attracted renewed interests because of the recent discovery of novel topological spin textures, for instance magnetic skyrmion [1][2][3][4][5][6] and chiral magnetic soliton lattice. 7-9) A helical magnetic structure is stabilized by the magnetic frustration 10, 11) and/or DzyaloshinskyMoriya (DM) interaction.…”

“…Non-colinear incommensurate magnetic structures, such as a helical magnetic structure, have attracted renewed interests because of the recent discovery of novel topological spin textures, for instance magnetic skyrmion [1][2][3][4][5][6] and chiral magnetic soliton lattice. 7-9) A helical magnetic structure is stabilized by the magnetic frustration 10, 11) and/or DzyaloshinskyMoriya (DM) interaction.…”