Field-Driven Quantum Criticality in the Spinel Magnet ${\mathrm{ZnCr}}_{2}{\mathrm{Se}}_{4}$

Field-Driven Quantum Criticality in the Spinel Magnet ${ZnCr}_{2} {Se}_{4}$

C. C. Gu, Z. Y. Zhao, X. L. Chen, M. Lee, E. S. Choi, Y. Y. Han, L. S. Ling, L. Pi, Y. H. Zhang, G. Chen, Z. R. Yang, H. D. Zhou, and X. F. Sun

Phys. Rev. Lett. 120, 147204 – Published 5 April 2018

Abstract

We report detailed dc and ac magnetic susceptibilities, specific heat, and thermal conductivity measurements on the frustrated magnet ${ZnCr}_{2} {Se}_{4}$ . At low temperatures, with an increasing magnetic field, this spinel material goes through a series of spin state transitions from the helix spin state to the spiral spin state and then to the fully polarized state. Our results indicate a direct quantum phase transition from the spiral spin state to the fully polarized state. As the system approaches the quantum criticality, we find strong quantum fluctuations of the spins with behaviors such as an unconventional $T^{2}$ -dependent specific heat and temperature-independent mean free path for the thermal transport. We complete the full phase diagram of ${ZnCr}_{2} {Se}_{4}$ under the external magnetic field and propose the possibility of frustrated quantum criticality with extended densities of critical modes to account for the unusual low-energy excitations in the vicinity of the criticality. Our results reveal that ${ZnCr}_{2} {Se}_{4}$ is a rare example of a 3D magnet exhibiting a field-driven quantum criticality with unconventional properties.

Received 19 September 2017
Revised 8 March 2018

DOI:https://doi.org/10.1103/PhysRevLett.120.147204

Physics Subject Headings (PhySH)

Frustrated magnetism Magnetism

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

C. C. Gu¹, Z. Y. Zhao^2,3, X. L. Chen¹, M. Lee^4,5, E. S. Choi⁴, Y. Y. Han¹, L. S. Ling¹, L. Pi^1,2,7, Y. H. Zhang^1,7, G. Chen^6,7,*, Z. R. Yang^1,7,8,†, H. D. Zhou^9,10,‡, and X. F. Sun^2,7,8,§

¹Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, Anhui 230031, People’s Republic of China
²Department of Physics, Hefei National Laboratory for Physical Sciences at Microscale, and Key Laboratory of Strongly-Coupled Quantum Matter Physics (CAS), University of Science and Technology of China, Hefei, Anhui 230026, People’s Republic of China
³Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, People’s Republic of China
⁴National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32306-4005, USA
⁵Department of Physics, Florida State University, Tallahassee, Florida 32306-3016, USA
⁶State Key Laboratory of Surface Physics and Department of Physics, Center for Field Theory and Particle Physics, Fudan University, Shanghai, 200433, China
⁷Collaborative Innovation Center of Advanced Microstructures, Nanjing, Jiangsu 210093, People’s Republic of China
⁸Institute of Physical Science and Information Technology, Anhui University, Hefei, Anhui 230601, People’s Republic of China
⁹Key laboratory of Artificial Structures and Quantum Control (Ministry of Education), School of Physics and Astronomy, Shanghai JiaoTong University, Shanghai 200240, China
¹⁰Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996-1200, USA