2019Physical Review Materials

Raman spectroscopy evidence for dimerization and Mott collapse in α-RuCl₃ under pressures

Gaomin Li, Xiaobin Chen, Yuan Gan, Fenglei Li, Mingqi Yan, Fan Ye, Shenghai Pei, Yujun Zhang, Le Wang, Huimin Su, Junfeng Dai, Yuanzhen Chen, Youguo Shi, XinWei Wang, Liyuan Zhang, Shanmin Wang, Dapeng Yu, Fei Ye, Jia-Wei Mei, Mingyuan Huang

Physical Review Materials · 3, 023601 (2019)

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DOI 10.1103/physrevmaterials.3.023601

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Introduction

Pressure-dependent Raman spectra resolve two transitions in α-RuCl₃. New modes accompany a stacking change; at higher pressure, in-plane Ru–Ru dimerization accompanies the collapse of the Mott state. Second-harmonic generation independently tests inversion-symmetry breaking.

A closer reading

A new Raman mode alone cannot uniquely determine a structure. An independent optical symmetry test and the signatures of bond dimerization give separate footing to the structural and electronic parts of the interpretation.