Elastocaloric signatures of symmetric and antisymmetric strain-tuning of quadrupolar and magnetic phases in DyB ₂ C ₂

Journal Article · Tue Aug 22 00:00:00 EDT 2023 · Proceedings of the National Academy of Sciences of the United States of America

DOI:https://doi.org/10.1073/pnas.2302800120· OSTI ID:1996287

Ye, Linda ^[1]; Sun, Yue  ^[2]; Sunko, Veronika  ^[2]; Rodriguez-Nieva, Joaquin F.  ^[3]; Ikeda, Matthias S.  ^[1]; Worasaran, Thanapat ^[1]; Sorensen, Matthew E. ^[4]; Bachmann, Maja D. ^[1]; Orenstein, Joseph  ^[2]; Fisher, Ian R.  ^[1]

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1. Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA 94305, Department of Applied Physics, Stanford University, Stanford, CA 94305
2. Department of Physics, University of California, Berkeley, CA 94720, Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
3. Department of Physics, Stanford University, Stanford, CA 94305
4. Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA 94305, Department of Physics, Stanford University, Stanford, CA 94305

The adiabatic elastocaloric effect measures the temperature change of a given system with strain and provides a thermodynamic probe of the entropic landscape in the temperature-strain space. Here, we demonstrate that the DC bias strain-dependence of AC elastocaloric effect allows decomposition of the latter into symmetric (rotation-symmetry-preserving) and antisymmetric (rotation-symmetry-breaking) strain channels, using a tetragonal $f$ -electron intermetallic DyB ${}_2$ C ${}_2$ —whose antiferroquadrupolar order breaks local fourfold rotational symmetries while globally remaining tetragonal—as a showcase example. We capture the strain evolution of its quadrupolar and magnetic phase transitions using both singularities in the elastocaloric coefficient and its jumps at the transitions, and the latter we show follows a modified Ehrenfest relation. We find that antisymmetric strain couples to the underlying order parameter in a biquadratic (linear-quadratic) manner in the antiferroquadrupolar (canted antiferromagnetic) phase, which are attributed to a preserved (broken) global tetragonal symmetry, respectively. The broken tetragonal symmetry in the magnetic phase is further evidenced by elastocaloric strain-hysteresis and optical birefringence. Additionally, within the staggered quadrupolar order, the observed elastocaloric response reflects a quadratic increase of entropy with antisymmetric strain, analogous to the role magnetic field plays for Ising antiferromagnetic orders by promoting pseudospin flips. Our results demonstrate AC elastocaloric effect as a compact and incisive thermodynamic probe into the coupling between electronic degrees of freedom and strain in free energy, which holds the potential for investigating and understanding the symmetry of a wide variety of ordered phases in broader classes of quantum materials.

• Sponsoring Organization: USDOE
• Grant/Contract Number: AC02-05CH11231
• OSTI ID: 1996287
• Journal Information: Proceedings of the National Academy of Sciences of the United States of America, Journal Name: Proceedings of the National Academy of Sciences of the United States of America Vol. 120 Journal Issue: 35; ISSN 0027-8424
• Publisher: Proceedings of the National Academy of Sciences
• Country of Publication: United States
• Language: English