A quantum magnetic analogue to the critical point of water
| Autor: | Jiménez, J. Larrea, Crone, S. P. G., Fogh, E., Zayed, M. E., Lortz, R., Pomjakushina, E., Conder, K., Läuchli, A. M., Weber, L., Wessel, S., Honecker, A., Normand, B., Rüegg, Ch., Corboz, P., Rønnow, H. M., Mila, F. |
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| Rok vydání: | 2020 |
| Předmět: | |
| Zdroj: | Nature {\bf 592}, 370 (2021) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1038/s41586-021-03411-8 |
| Popis: | At the familiar liquid-gas phase transition in water, the density jumps discontinuously at atmospheric pressure, but the line of these first-order transitions defined by increasing pressures terminates at the critical point, a concept ubiquitous in statistical thermodynamics. In correlated quantum materials, a critical point was predicted and measured terminating the line of Mott metal-insulator transitions, which are also first-order with a discontinuous charge density. In quantum spin systems, continuous quantum phase transitions (QPTs) have been investigated extensively, but discontinuous QPTs have received less attention. The frustrated quantum antiferromagnet SrCu$_2$(BO$_3$)$_2$ constitutes a near-exact realization of the paradigmatic Shastry-Sutherland model and displays exotic phenomena including magnetization plateaux, anomalous thermodynamics and discontinuous QPTs. We demonstrate by high-precision specific-heat measurements under pressure and applied magnetic field that, like water, the pressure-temperature phase diagram of SrCu$_2$(BO$_3$)$_2$ has an Ising critical point terminating a first-order transition line, which separates phases with different densities of magnetic particles (triplets). We achieve a quantitative explanation of our data by detailed numerical calculations using newly-developed finite-temperature tensor-network methods. These results open a new dimension in understanding the thermodynamics of quantum magnetic materials, where the anisotropic spin interactions producing topological properties for spintronic applications drive an increasing focus on first-order QPTs. Comment: 8+4 pages, 4+3 figures |
| Databáze: | arXiv |
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