We report on comprehensive results identifying the ground state of a triangular-lattice structured YbZnGaO4 to be spin glass, including no long-range magnetic order, prominent broad excitation continua, and absence of magnetic thermal conductivity. More crucially, from the ultralow-temperature a.c. susceptibility measurements, we unambiguously observe frequency-dependent peaks around 0.1 K, indicating the spin-glass ground state. We suggest this conclusion to hold also for its sister compound YbMgGaO4, which is confirmed by the observation of spin freezing at low temperatures. We consider disorder and frustration to be the main driving force for the spin-glass phase.
@article{arxiv.1709.00256,
title = {Spin-glass ground state in a triangular-lattice compound YbZnGaO$_4$},
author = {Zhen Ma and Jinghui Wang and Zhao-Yang Dong and Jun Zhang and Shichao Li and Shu-Han Zheng and Yunjie Yu and Wei Wang and Liqiang Che and Kejing Ran and Song Bao and Zhengwei Cai and P. Čermák and A. Schneidewind and S. Yano and J. S. Gardner and Xin Lu and Shun-Li Yu and Jun-Ming Liu and Shiyan Li and Jian-Xin Li and Jinsheng Wen},
journal= {arXiv preprint arXiv:1709.00256},
year = {2018}
}