Berlin 2018 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 50: Quantum-Critical Phenomena I
TT 50.12: Vortrag
Mittwoch, 14. März 2018, 12:45–13:00, H 3005
Quantum criticality in the spin-1/2 Heisenberg chain system CuPzN — Oliver Breunig1, Markus Garst2,3, Andreas Klümper4, Jens Rohrkamp1, Mark M. Turnbull5, and •Thomas Lorenz1 — 1II. Physikalisches Institut, Universität zu Köln, Germany — 2Institut für Theoretische Physik, Universität zu Köln, Germany — 3Institut für Theoretische Physik, Universität Dresden, Germany — 4Fachbereich C Physik, Bergische Universität Wuppertal, Germany — 5Carlson School of Chemistry, Clark University, Worcester, USA
The magnetic insulator copper pyrazine dinitrate (CuPzN) is one of the best experimental realizations of the Heisenberg spin-1/2 chain model. Its weak antiferromagnetic coupling J of about 10 K provides a unique opportunity for a quantitative comparison between theory and experiment. Here, we study thermodynamic properties with a particular focus on the magnetic-field induced quantum phase transition at 14 T [1]. Thermal expansion, magnetostriction, specific heat, magnetization and magnetocaloric measurements almost perfectly agree with predictions from exact Bethe-Ansatz results. On approaching the critical field, thermodynamics obeys the quantum critical scaling behavior expected from effective field theory. In particular, the magnetic-field and pressure dependent Grüneisen parameters diverge in a characteristic manner. Our study instructively illustrates fundamental principles of quantum critical thermodynamics and also reveals the influence of corrections to scaling.
Funded by the DFG via FOR 960, FOR2316, CRC1143, and CRC1238.
O. Breunig et al., arxiv1709.00274 (Sci. Adv., to appear).