Magneto-caloric effects, quantum critical points, and the Berezinsky-Kosterlitz-Thouless transition in 2D coupled spin dimer systems

Abstract

Spin dimer systems are a promising playground for the detailed study of quantum phase transitions. Using the magnetic field as the tuning parameter it is in principle possible to observe a crossover from the characteristic scaling near critical points to the behavior of a finite temperature phase transition. In this work we study two-dimensional coupled spin dimer systems by comparing numerical quantum Monte Carlo simulations with analytical calculations of the susceptibility, the magneto-caloric effect, and the helicity modulus. The magneto-caloric behavior of the magnetization with temperature can be used to determine the critical fields with high accuracy, but the critical scaling does not show the expected logarithmic corrections. The zeros of the cooling rate are an excellent indicator of the competition between quantum criticality and vortex physics, but they are not directly associated with the quantum phase transition or the finite temperature Berezinsky-Kosterlitz-Thouless transition. The results give a unified picture of the full quantum and finite temperature phase diagram.

9 pages with 10 figures. New version includes updated figures, data, and references. For more information and the latest version see http://www.physik.uni-kl.de/eggert/papers/index.html

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Cited by in corpus (8)

• Adiabatic physics of an exchange-coupled spin-dimer system: magnetocaloric effect, zero-point fluctuations, and possible two-dimensional universal behavior
• Quantum criticality of spinons
• Frustrated honeycomb-lattice bilayer quantum antiferromagnet in a magnetic field: Unconventional phase transitions in a two-dimensional isotropic Heisenberg model
• Grüneisen Parameters: origin, identity and quantum refrigeration
• Tunable anisotropic superfluidity in an optical kagome superlattice
• Mixed-spin system with supersolid phases: Magnetocaloric effect and thermal properties
• Thermodynamics and renormalized quasi-particles in the vicinity of the dilute Bose gas quantum critical point in two dimensions
• Entanglement of Hard-Core Bosons in Bipartite Lattices