Probing multipolar order in the candidate altermagnet MnF$_2$ through the elastocaloric effect under strain

TL;DR

This paper investigates the altermagnetic order in MnF$_2$ using elastocaloric effects under strain, combining experiments and modeling to identify a finite-temperature critical point, advancing understanding of altermagnetic quantum criticality.

Contribution

It introduces a thermodynamic method to probe altermagnetic order and criticality in MnF$_2$ through elastocaloric measurements, supported by theoretical modeling and first-principles calculations.

Findings

Identification of a finite-temperature altermagnetic critical point in MnF$_2$

Establishment of elastocaloric effect as a thermodynamic probe for altermagnetism

Insights into altermagnetic quantum criticality in $d$-wave materials

Abstract

Altermagnets break a combination of time-reversal and rotational symmetries without generating a net magnetization. As such, the order parameter of $d$-wave altermagnets has the same symmetry as magnetic multipoles, and couples to the product of a magnetic field and uniaxial strain. We combine elastocaloric experiments, free-energy modeling, and first-principles calculations on MnF$_2$ to establish a thermodynamic probe of the predicted finite-temperature altermagnetic critical point. These results pave the way to explore altermagnetic quantum criticality in $d$-wave materials and beyond.