AC elastocaloric investigation of the antiferroquadrupolar order in DyB2C2*

Elastic strain applied in situ has emerged in recent years as a versatile tuning parameter for quantum materials. To address the key question of how strain perturbs various strongly correlated electronic phases, a thermodynamic probe that can be implemented under strained conditions is highly desirable. Our group has developed an AC elastocaloric (EC) technique that measures adiabatic temperature oscillations induced by a modulating strain, with the simultaneous application of a DC bias strain as the tuning parameter [1]. Here we use this new technique to investigate the response of DyB₂C₂, a prototypical rare earth system hosting an antiferroquadrupole order [2]. In addition to unraveling a strain-tuning of the underlying quadrupolar and magnetic phase transitions, we have also uncovered an unusual enhancement of entropy with strain in the antiferroquadrupole phase. Our findings suggest that strain can serve as an incisive probe of antiferroquadrupolar systems, and, more broadly, demonstrate the rich prospects that may be accessed by EC measurements.

[1] M. S. Ikeda et al., Rev. Sci. Instrum. 90, 083902 (2019).

[2] H. Yamauchi et al., J. Phys. Soc. Jpn. 68, 2057-2066 (1998).