Magnetic anisotropy of chiral magnet Yb(Ni$_{1-x}$Cu$_x$)$_{3}$Al$_{9}$ at high magnetic fields

TL;DR

This study investigates the magnetic anisotropy of the chiral magnet Yb(Ni$_{1-x}$Cu$_x$)$_{3}$Al$_{9}$ at high magnetic fields, revealing the role of crystalline electric field effects and exchange interactions in its magnetic behavior.

Contribution

The paper introduces a crystalline electric field model including the $B_{66}$ term and orbital-dependent exchange interactions to explain the magnetization processes and susceptibility in Yb(Ni$_{1-x}$Cu$_x$)$_{3}$Al$_{9}$.

Findings

Magnetization along the c-axis overtakes perpendicular magnetization above 4 T.

The $B_{66}$ term explains the magnetization overtaking behavior.

Orbital-dependent exchange interactions account for temperature dependence of susceptibility.

Abstract

We have measured the magnetization of rare-earth chiral magnets Yb(Ni$_{1-x}$Cu$_x$)$_{3}$Al$_{9}$ for $x$=0 and 0.06 up to 14.5 T. Magnetization for the field direction $H \parallel c$, which is the hard axis at low temperatures and low fields, overtakes the easy axis magnetization for $H \perp c$ above $\sim$4 T. We analyzed this overtaking of the magnetization curves by considering a crystalline electric field model. It is shown that the $B_{66}$ term, which connects the $|\pm5/2 \rangle$ and the $|\mp7/2\rangle$ states through the off-diagonal matrix element, is responsible for the characteristic magnetization process in this compound. We also introduce orbital dependent exchange interactions to explain the temperature dependence of magnetic susceptibility.