Probing Multipolar Order in the Candidate Altermagnet MnF_{2} through the Elastocaloric Effect under Strain.

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.