Disorder-Induced Spin Excitation Continuum and Spin-Glass Ground State in the Inverse Spinel CuGa2O4

Published

July 10, 2025

Author(s)

Zhentao Huang, Zhijun Xu, Shuaiwei Li, Qingchen Duan, Junbo Liao, Song Bao, Yanyan Shangguan, Bo Zhang, Hao Xu, Shufan Cheng, Zihang Song, Shuai Dong, Maofeng Wu, M. B. Stone, Yiming Qiu, Ruidan Zhang, Guangyong Xu, Zhen Ma, G. Gu, J. Tranquada, Jinsheng Wen

Abstract

Spinel-structured compounds serve as prototypical examples of highly frustrated systems and are promising candidates for realizing the long-sought quantum spin liquid (QSL) state. However, structural disorder is inevitable in many real QSL candidates and its impact remains a topic of intense debate. In this work, we conduct comprehensive investigations on CuGa2O4, a spinel compound with significant structural disorder, focusing on its thermodynamic properties and spectroscopic behaviors. No long-range magnetic order is observed down to ∼80 mK, as evidenced by magnetic susceptibility, specific-heat, and elastic neutron scattering measurements. More intriguingly, inelastic neutron scattering experiments reveal a broad gapless continuum of magnetic excitations around the Brillouin zone boundary, resembling the magnetic excitation spectra expected for a QSL. Nevertheless, a spin-freezing transition at Tf ≈ 0.88 K is identified from the cusp in the dc susceptibility curves, where a bifurcation between zero-field-cooling and field-cooling curves occurs. Furthermore, ac susceptibility measurements show a peak close to Tf at low frequency, which shifts to higher temperature with increasing frequency. These results show that CuGa2O4 has a spin-glass ground state, consistent with the establishment of short-range order inferred from the specific-heat measurements. Collectively, these results illustrate the crucial role of disorder in defining the excitation spectrum out of the disordered ground state. Our findings shed light onto the broader class of AB2O4 spinels and advance our understanding of the spin dynamics in magnetically disordered systems.

Citation

Physical Review B

Volume

112

Issue

3

Pub Type

Journals

Download Paper

https://doi.org/10.1103/1xtf-wg3q

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Keywords

spinel, quantum spin liquid, neutron scattering

Citation

Huang, Z. , Xu, Z. , Li, S. , Duan, Q. , Liao, J. , Bao, S. , Shangguan, Y. , Zhang, B. , Xu, H. , Cheng, S. , Song, Z. , Dong, S. , Wu, M. , Stone, M. , Qiu, Y. , Zhang, R. , Xu, G. , Ma, Z. , Gu, G. , Tranquada, J. and Wen, J. (2025), Disorder-Induced Spin Excitation Continuum and Spin-Glass Ground State in the Inverse Spinel CuGa2O4, Physical Review B, [online], https://doi.org/10.1103/1xtf-wg3q, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=959868 (Accessed July 12, 2025)