Regensburg 2022 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 23: Frustrated Magnets - General
TT 23.7: Talk
Wednesday, September 7, 2022, 16:45–17:00, H22
Magneto-thermodynamics of the J1-J2 Heisenberg antiferromagnet on the square lattice — •Andreas Honecker1, Johannes Richter2,3, Jürgen Schnack4, Alexander Wietek3, and Mike E. Zhitomirksy5 — 1LPTM, CY Cergy Paris Université, France — 2Institut für Physik, Universität Magdeburg, Germany — 3Max Planck Institute for the Physics of Complex Systems, Dresden, Germany — 4Fakultät für Physik, Universität Bielefeld, Germany — 5Université Grenoble Alpes, CEA, IRIG, PHELIQS, France
We investigate the finite-temperature properties of the J1-J2 Heisenberg antiferromagnet on the square lattice in the presence of an external magnetic field. We focus on the highly frustrated regime around J2 ≈ J1/2. The H-T phase diagram is investigated with particular emphasis on the finite-temperature transition into the “up-up-up-down” state that is stabilized by thermal and quantum fluctuations and manifests itself as a plateau at one half of the saturation magnetization in the quantum case. Furthermore, we discuss the enhanced magnetocaloric effect associated to the ground-state degeneracy that arises at the saturation field for J2=J1/2. Computations for the spin-1/2 system are carried out using finite-temperature Lanczos and quantum typicality approaches.