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MA: Fachverband Magnetismus
MA 8: Altermagnets II
MA 8.8: Vortrag
Montag, 9. März 2026, 17:00–17:15, HSZ/0002
Elastocaloric probing and tuning of multipolar order in the altermagnet MnF2 — •Rahel Ohlendorf1,2, Luca Buiarelli3, Hilary M. L. Noad1, Andrew P. Mackenzie1,4, Rafael M. Fernandes5, Turan Birol3, Jörg Schmalian6, and Elena Gati1,2,7 — 1Max Planck Institute for Chemical Physics of Solids, Dresden, Germany — 2Technische Universität, Dresden, Germany — 3University of Minnesota, Minneapolis, USA — 4University of St Andrews, UK — 5University of Illinois Urbana-Champain, Urbana, USA — 6Karlsruhe Institute of Technology, Karlsruhe, Germany — 7Goethe Universität, Frankfurt, Germany
Altermagnets break time-reversal symmetry without net magnetization [1], with the order parameter described by the ferroic ordering of multipoles rather than dipoles. In d-wave altermagnets, the predicted ferrooctupolar order couples to magnetic field and strain. In this talk, we demonstrate that elastocaloric experiments under strain and magnetic field are a powerful thermodynamic and symmetry-sensitive probe of the finite-temperature ferrooctupolar critical point. We resolve elastocaloric signatures of altermagnetic crossover lines and entropy accumulation. By combining our experiments with DFT calculations, we provide a microsopic explanation for the size of the observed thermodynamic effects. As a result, we outline the route to stronger thermodynamic responses in insulating and metallic altermagnets (both d-wave and g-wave), establishing elastocaloric measurements as a key probe of altermagnetic criticality.
[1] L. Šmejkal et al., Phys. Rev. X 12, 031042 (2022)
Keywords: altermagnetism; elastocaloric effect; MnF$_2$; multipolar order; DFT