Field Induced Chirality in the Helix Structure ofDy/YMultilayer Films and Experimental Evidence for Dzyaloshinskii-Moriya Interaction on the Interfaces

Abstract

Polarized neutron scattering experiments have demonstrated that Dy/Y multilayer structures possess a coherent spin helix with a preferable chirality induced by the magnetic field. The average chirality, being proportional to the difference in the left- and right-handed helix population numbers, is measured as a polarization-dependent asymmetric part of the magnetic neutron scattering. The magnetic field applied in the plane of the sample upon cooling below T(N) is able to repopulate the otherwise equal population numbers for the left- and right-handed helixes. The experimental results strongly indicate that the chirality is caused by Dzyaloshinskii-Moriya interaction due to the lack of the symmetry inversion on the interfaces.

Field-induced chirality in the helix structure of Ho/Y multilayers

“…The x-ray characterizations clearly indicate that the interfaces of all of the examined Ho/Y SL are of good quality, but are also partly intermixed and thus fulfill the necessary conditions for the occurence of a non-zero DM energy contribution at the interfaces. On the other hand, the chirality of the investigated samples does not exceed a maximum value of about 13% what is twice as less that in Dy/Y multilayers [10,11]. We explain this decrease by a strong influence of the crystal-field anisotropy in Ho layers.…”

“…A few years ago Grigoriev et al have demonstrated that Dy/Y magnetic multilayers (MMLs) possess a coherent spin helix with a preferable chirality induced by a magnetic field [10]. It was shown that a magnetic field applied in the plane of the sample upon cooling below T N is able to repopulate the otherwise equal population numbers for the left-and righthanded helixes.…”

“…The new impulse for the investigations of the rare earth superlattice was stimulated by the observation of effects caused by magnetic interfaces, such as, the enhanced interfacial magnetic order [7], the twisted magnetization states [8] and the surface-induced DzyaloshinskiiMoriya interaction [9][10][11]. A few years ago Grigoriev et al have demonstrated that Dy/Y magnetic multilayers (MMLs) possess a coherent spin helix with a preferable chirality induced by a magnetic field [10].…”

“…At this configuration with the polarization of the incident beam aligned along the direction of the applied field (P 0 Q), the corresponding scattered intensities, [I + = I(Q, +P 0 ) and I − = I(Q, −P 0 )], are due to scattering on either the right-or left-handed domains, respectively. The average chirality, which is proportional to the difference in the population of the left-and right-handed helices, was measured as the polarization-dependent asymmetric part of the magnetic neutron-scattering cross section [10]. Thus we introduce here a chiral parameter directly related to the measured intensities and to the imbalance between the left-and right-handed domains:…”

The quantum nature of skyrmions and half-skyrmions in Cu2OSeO3

“…Besides the renormalization of the helix period, this coupling actually reverses the magnetic handedness of the system, a key aspect that can be confirmed experimentally with polarized neutrons [39][40][41][42][43][44] . Indeed, while preparing the final version of our manuscript, we became aware of a new experimental study by Dyadkin et al 45 , which confirms our theoretical prediction for the sign of the magnetic handedness of Cu 2 OSeO 3 .…”