Abstract
The authors demonstrate the vector-field control of the magnetic screw axis in a chiral helimagnet and show that the spiral period varies the orientation of the screw axis with respect to the principal crystallographic axes.
Highlights
Magnetic skyrmions are topological spin vortices in chiral and polar magnetic materials that attract significant interest due to their promising properties for magnetic storage and other spintronic applications [1,2,3]
The ground-state magnetic structures of B20-type systems are well explained by the Bak-Jensen model that takes into account the interplay between Heisenberg exchange interaction, antisymmetric Dzyaloshinskii-Moriya interaction (DMI) [19,20], anisotropic exchange interaction (AEI), and cubic anisotropy [21]
Experimentally-determined values of the exchange stiffness Aex = 8.78 pJ/m DMI constant D = 1.58 mJ/m2, cubic anisotropy constant Kc1 = 10 kJ/m3, and saturation magnetization Ms = 384 kA/m were taken from the microwave spin-wave spectroscopy [51]
Summary
Magnetic skyrmions are topological spin vortices in chiral and polar magnetic materials that attract significant interest due to their promising properties for magnetic storage and other spintronic applications [1,2,3]. The weak cubic anisotropy determines the spin-wave gap and some additional peculiarities of the helix axis orientation under a magnetic field, while the exchange, DMI, and AEI are responsible for the helical magnetic structure and its orientation relative to crystallographic axes [22]. The AEI constant is estimated experimentally from the helical-to-conical transition field Bc1 as F = 2SgμBBc1/Q2, where g is the Landé factor and μB is the Bohr magneton This formula leads to the estimated low-temperature value of F ≈ −45 meV Å2 for FeGe [26]. We argue that the observed in-plane variation in Q of order 1% is determined by the higher order AEI in accord with the expectation of the Bak-Jensen model
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