arXiv subjects

Weiyi Yun

Publications and source records attributed to Weiyi Yun.

2 recordsLinked to original sources

arXiv2026

Observation of g-wave altermagnetic multipole

Over the past few years, altermagnets have emerged as a new class of collinear magnets with broken time-reversal symmetry, offering novel opportunities for spintronics beyond conventional magnets. Rather than from net magnetization, as in ferromagnets, the unconventional time-reversal symmetry breaking of altermagnets originates from antiferroic magnetic dipoles locked to higher-order multipoles. Here we report the direct visualization of a $g$-wave altermagnetic multipole in the canonical altermagnet CrSb. Combining high-energy synchrotron X-ray diffraction with valence electron density (VED) analysis, we uncover a pronounced directional anisotropy of the VED distribution alternating between Cr sublattices. This evidences the antiferroic order of electric hexadecapoles predicted in $g$-wave altermagnets. Its coexistence with antiferroic magnetic dipoles induces ferroic magnetic multipoles, as probed by polarized neutron diffraction. We further identify a microscopic model of altermagnetism that directly relates the $g$-wave multipole and the $g$-wave spin splitting. Through direct observation and quantification of multipoles, this study provides a real-space fingerprint of altermagnetism and establishes a general probe of hidden multipole order in quantum materials.

cond-mat.str-el↗

arXiv2026

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

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.

cond-mat.str-el↗