Stripe antiferromagnetism in van der Waals metal HoTe3 decoupled from charge density wave order

TL;DR

This study uncovers two distinct antiferromagnetic phases in HoTe3 with different stacking orders, demonstrating that in this van der Waals compound, magnetism is decoupled from charge density wave order, unlike in related materials.

Contribution

The paper identifies and characterizes two antiferromagnetic phases in HoTe3 with different stacking arrangements, revealing decoupled magnetic and charge density wave orders in this layered vdW compound.

Findings

Two AFM phases with different stacking orders identified

No evidence of coupling between magnetism and CDW in HoTe3

Magnetic propagation vectors and anisotropy are characterized

Abstract

The $R\mathrm{Te}_3$ ($R = \text{rare earth}$) family of layered van der Waals (vdW) compounds hosts coexisting magnetic and charge density wave (CDW) orders, yet the interplay between these degrees of freedom remains little explored. Combining polarized and unpolarized neutron diffraction on single-crystal $\mathrm{HoTe}_3$, we identify two distinct antiferromagnetic (AFM) phases, both exhibiting a collinear $\uparrow\uparrow\downarrow\downarrow$ motif within individual vdW layers. The two phases are distinguished by the vdW stacking of magnetic layers: ferromagnetic (FM) stacking in the higher-temperature AFM-II phase, here termed ``vertical-stripe'', and AFM stacking in the AFM-I ground state, here termed ``tilted-stripe''; the two phases have propagation vectors $\boldsymbol{q}_{\mathrm{m2}} = (0.48, 0, 0)$ and $\boldsymbol{q}_{\mathrm{m1}} = (0.5, 0.5, 0)$, respectively. In contrast to the CDW-driven exotic magnetism in $\mathrm{DyTe}_3$, $\mathrm{TbTe}_3$, and $\mathrm{GdTe}_3$, we find no evidence for coupling between magnetism and CDW in $\mathrm{HoTe}_3$. The relative alignment between AFM and CDW propagation vectors, as well as single-ion anisotropy, are likely essential for generating coupled spin/charge orders in layered vdW systems.