Low-temperature spin excitations in frustrated ZnCr${}_{2}$O${}_{4}$ probed by high-field thermal conductivity

Low-temperature spin excitations in frustrated ZnCr $_{2}$ O $_{4}$ probed by high-field thermal conductivity

H. D. Zhou, Z. Y. Zhao, X. F. Sun, M. Nieto Suarez, B. Rivas-Murias, V. Tsurkan, J. Deisenhofer, V. S. Zapf, and F. Rivadulla

Phys. Rev. B 87, 174436 – Published 31 May 2013

Abstract

The magnetoelastic excitations of spin frustrated ZnCr $_{2}$ O $_{4}$ are studied by the magnetic field dependence of the thermal conductivity $k$ down to 50 mK. Above the first-order magnetostructural transition at $T_{N, S}$ ≈ 12.5 K, spin fluctuations are strongly coupled to acoustic phonons, leading to a glasslike dependence of $k$ ( $T$ ), up to $Θ_{CW}$ . In the symmetry broken phase below $T_{N, S}$ , $k$ shows a dominant magnetic contribution even at the lowest temperatures probed in this work. Application of a magnetic field above 2.5 T destabilizes the spin-bond structure, leading to a sudden increase and a nonconventional temperature dependence of the thermal conductivity. The possibility of the coexistence of gapped and gapless excitations in this magnetic phase is discussed.

Received 5 April 2013

DOI:https://doi.org/10.1103/PhysRevB.87.174436

Authors & Affiliations

H. D. Zhou^1,2, Z. Y. Zhao³, X. F. Sun³, M. Nieto Suarez⁴, B. Rivas-Murias⁴, V. Tsurkan^5,6, J. Deisenhofer⁵, V. S. Zapf⁷, and F. Rivadulla^4,*

¹Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996-1200, USA
²National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32306-4005, USA
³Hefei National Laboratory for Physical Sciences at the Microscale, Heifei, Anhui 230026, China
⁴Centro de Investigación en Química-Biológica y Materiales Moleculares (CIQUS), c/Jenaro de la Fuente s/n, Campus Vida, 15782-Santiago de Compostela, Spain
⁵Experimental Physics V, Centre for Electronic Correlations and Magnetism, University of Augsburg, Universitätsstr. 1, 86159 Augsburg, Germany
⁶Institute of Applied Physics, Academy of Sciences of Moldova, MD-2028 Chisinau, Republic of Moldova
⁷National High Magnetic Field Laboratory, Los Alamos National Laboratory, New Mexico, USA

^*Corresponding author: f.rivadulla@usc.es

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Vol. 87, Iss. 17 — 1 May 2013

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