Probing a two-dimensional soft ferromagnet Cr$_2$Ge$_2$Te$_6$ by a tuning fork resonator

TL;DR

This study uses a quartz tuning-fork resonator to directly measure magnetic anisotropy in the 2D ferromagnet Cr$_2$Ge$_2$Te$_6$, revealing detailed angular dependence and establishing a new thermodynamic probing method.

Contribution

It introduces tuning-fork resonators as a sensitive tool for probing magnetic anisotropy and demonstrates their effectiveness on a layered ferromagnet, providing insights into spin and orbital contributions.

Findings

Magnetotropic susceptibility varies with temperature, field, and angle.

Angular profile shifts from cos(2θ) to a dip near saturation.

Cr$_2$Ge$_2$Te$_6$ serves as a reference for tuning-fork measurements.

Abstract

Magnetic anisotropy encodes key information about the free-energy landscape of magnetic materials, but its quantitative characterization often requires probes beyond conventional magnetometry. A quartz tuning-fork resonator provides direct access to the magnetotropic susceptibility. Here we use this technique to investigate the magnetic anisotropy of the layered ferromagnet Cr$_2$Ge$_2$Te$_6$. The temperature-, field-, and angle-dependent responses are consistently described by a quasi-two-dimensional (2D) easy-axis ferromagnetic model. In particular, the evolution of the magnetotropic susceptibility reveals how the angular profile changes from a conventional cos(2$\theta$) form to a pronounced dip structure as the magnetization approaches directional saturation. These results establishCr$_2$Ge$_2$Te$_6$ as an ideal reference system for tuning-fork-based magnetotropic measurements. More broadly, they provide a useful framework for distinguishing spin-origin anisotropy from orbital magnetism, as in the case of CsV3Sb5. Our work demonstrates that tuning-fork resonators offer a sensitive thermodynamic probe of the rotational stiffness of magnetization in anisotropic low-dimensional magnets.