QFS2016 Book of Abstracts

Abstracts

P1.16 Magnetization process, thermodynamics and magnetocaloric effect of the spin-1/2 XXZ Heisenberg cubooctahedron Karlova Katarina(1), Strecka Jozef(2), Madaras Tomas(3) P. J. ˇSaf´arik University, Faculty of Science, Institute of Physics, Park Angelinum 9, 040 01 Koˇsice, Slovakia Magnetic properties of the spin-1/2 XXZ Heisenberg cubooctahedron are examined using exact numerical diagonalization as a function of the exchange anisotropy. While the Ising cubooctahedron exhibits in a low-temperature magnetization curve only one-third magnetization plateau, another four intermediate plateaux can be found in magnetization curve of the Heisenberg cubooctahedron for arbitrary but non-zero exchange anisotropy. The novel plateaux generally extend over a wider range of magnetic fields with the exchange anisotropy. The Heisenberg cubooctahedron exhibits in a vicinity of all magnetization jumps anomalous thermodynamic behavior accompanied with a giant magnetocaloric effect. P1.17 Magneto-thermodynamic signatures of quantum critical points of the ferrimagnetic mixed-spin Heisenberg chains Strecka Jozef(1), Verkholyak Taras(2) 1) Institute of Physics, Faculty of Science, P.J. Safarik University, Park Angelinum 9, 040 01 Kosice, Slovakia 2) Institute for Condensed Matter Physics, National Academy of Sciences of Ukraine, 1 Svientsitskii Street, L’viv-11, 79011, Ukraine Thermodynamic properties of the ferrimagnetic mixed spin-(1/2,S) Heisenberg chains are examined using quantum Monte Carlo simulations. Zero-temperature magnetization curves involve two quantum critical points with magnetization cusps, which determine a breakdown of Lieb-Mattis ferrimagnetism and Luttinger spin liquid, respectively. Thermodynamic signatures of these quantum critical points are examined at finite temperatures. While the magnetization curve at non-zero temperatures is almost without any signature, other thermodynamic response functions (susceptibility, specific heat, entropy) provide a more clear evidence of quantum critical points through local maxima or minima, respectively.

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