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arXiv · 2502.15528

Lattice dynamics and spin-phonon coupling in the kagome spin ice HoAgGe

Shangfei Wu·Lingxiao Zhao·Wei Song·Mingshu Tan·Feng Jin·Tianping Ying·Jia-Xin Yin·Qingming Zhang
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Abstract

We employ polarization-resolved Raman spectroscopy and first-principles phonon calculations to study the lattice dynamics and spin-phonon coupling in the kagome spin ice compound HoAgGe. Upon cooling, HoAgGe shows transitions from a nonmagnetic state at 300 K to a partially magnetic-ordered phase below T2 = 11.6 K, eventually reaching a fully-magnetic ordered phase below T1 = 7 K. We detect eight of ten Raman-active phonon modes at room temperature, with frequencies consistent with first-principles phonon calculations. We find that the low-energy phonon modes harden upon cooling, soften slightly below T2, and finally harden again below T1, suggesting finite spin-phonon coupling in HoAgGe. Furthermore, one high-energy mode at 185 cm-1 with E' symmetry exhibits a Fano lineshape due to electron-phonon coupling. Our Raman results establish finite spin-phonon coupling and electron-phonon coupling in the magnetic phase of HoAgGe, providing a foundation for future studies of the novel field-induced phases at low temperatures in HoAgGe.

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Shangfei Wu, Lingxiao Zhao, Wei Song, Mingshu Tan, Feng Jin, Tianping Ying, Jia-Xin Yin, Qingming Zhang. 2025-02-21. Lattice dynamics and spin-phonon coupling in the kagome spin ice HoAgGe. https://doi.org/10.1103/physrevb.111.125116

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