Magnetothermal properties of the Heisenberg-Ising orthogonal-dimer chain with triangularXXZclusters

2012/03/31 by Vadim Ohanyan, Andreas Honecker, A. Honecker
Physics and Astronomy · #Advanced Condensed Matter Physics #Antiferromagnetism #Condensed matter physics #Dimer #Heisenberg model #Hexagonal lattice #Ising model #Magnetic field #Magnetic refrigeration #Magnetization #Mathematical physics #Nuclear magnetic resonance #Physics #Physics of Superconductivity and Magnetism #Quantum many-body systems #Quantum mechanics #Spins #cond-mat.stat-mech #cond-mat.str-el

paper · pdf · doi:10.1103/physrevb.86.054412

published as Phys.Rev.B 86,054412(2012) · 18 pages, 13 figures

openalex publication_date 2012/08/09 · arxiv created 2012/08/14 · arxiv updated 2012/08/15 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05

Abstract

We study a spin-1/2 model with triangular XXZ clusters on the orthogonal-dimer chain in the presence of an external magnetic field. First, we discuss the case where the triangular clusters are coupled via intermediate ``classical'' Ising spins. Diagonalization of the triangular XXZ clusters yields the exact ground states; finite-temperature properties are computed exactly by an additional transfer-matrix step. A detailed analysis reveals a large variety of ground states at magnetization M equal to fractions 0, 1/4, and 1/2 of the saturation magnetization M=1. Some of these ground states break translational symmetry spontaneously and give rise to doubling of the unit cell. In a second part, we present complementary numerical data for the spin-1/2 Heisenberg model on the orthogonal-dimer chain. We analyze several examples of T=0 magnetization curves, entropy as a function of temperature T and magnetic field, and the associated magnetic cooling rate. Comparison of the two models shows that in certain situations the simplified exactly solvable model yields a qualitatively or sometimes even quantitatively accurate description of the more challenging quantum model, including a case which may be relevant to experimental observations of an enhanced magnetocaloric effect in the two-dimensional compound SrCu₂(BO₃)₂.

Citations

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