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Raz Rivlis

Publications and source records attributed to Raz Rivlis.

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Skyrmion Phase Control by Magnetic Dipole-Dipole Interaction and Electric Field in Centrosymmetric Materials

Establishing precise control over the helicity and spatial configuration of magnetic skyrmions will be essential to realize their promise in classical, analog and quantum computation applications. In this work, we explore the role of magnetic dipole-dipole interactions, external electric fields, and magnetic fields in controlling these parameters within a triangular lattice centrosymmetric skyrmion host. We demonstrate that dipole-dipole interactions strongly favor Bloch helicity. Notably, a zero magnetic field skyrmion phase appears upon raising the dipole-dipole coupling strength, with substantial potential for cost-effective quantum device applications. We also report the emergence of a meron/antimeron lattice phase, in the absence of any Dzyaloshinskii-Moriya interaction. In contrast, applied electric fields stabilize high density N\'eel skyrmion crystals. The interplay between dipole-dipole interactions and external electric fields creates a continuous transition between the two skyrmion types, rather than an abrupt switch. Applied electric fields can therefore be used as a continuous tuning mechanism for skyrmion helicity, and hence a control handle for tuning two-level systems in skyrmion qubits.

cond-mat.str-el

Giant and negative magnetoresistances in conical magnets

We study magnetotransport in conical helimagnet crystals. Spin dependent magnetoresistance exhibits dramatic properties for high and low electron concentrations at different temperatures. For spin up electrons we find negative magnetoresistance despite only considering a single carrier type. For spin down electrons we observe giant magnetoresistance due to depletion of spin down electrons with an applied magnetic field. For spin up carriers, the magnetoresistance is negative, due to the increase in charge carriers with a magnetic field. In addition, we investigate spin dependent Hall effect. If a magnetic field reaches some critical value for spin down electrons, giant Hall resistance occurs, i.e., Hall current vanishes. This effect is explained by the absence of spin down carriers. For spin up carriers, the Hall constant dramatically decreases with field, due to the increase in spin up electron density. Because of the giant spin dependent magnetoresistance and Hall resistivity, conical helimagnets could be useful in spin switching devices.

cond-mat.mes-hall