Quantum critical scaling at a Bose-glass/superfluid transition: theory and experiment on a model quantum magnet

Abstract

In this paper we investigate the quantum phase transition from magnetic Bose glass to magnetic Bose-Einstein condensation induced by a magnetic field in NiCl2.4SC(NH2)2 (dichloro-tetrakis-thiourea-Nickel, or DTN), doped with Br (Br-DTN) or site diluted. Quantum Monte Carlo simulations for the quantum phase transition of the model Hamiltonian for Br-DTN, as well as for site-diluted DTN, are consistent with conventional scaling at the quantum critical point and with a critical exponent z verifying the prediction z=d; moreover the correlation length exponent is found to be nu = 0.75(10) and the order parameter exponent to be beta = 0.95(10). We investigate the low-temperature thermodynamics at the quantum critical field of Br-DTN both numerically and experimentally, and extract the power-law behavior of the magnetization and of the specific heat. Our results for the exponents of the power laws, as well as previous results for the scaling of the critical temperature to magnetic ordering with the applied field, are incompatible with the conventional crossover-scaling Ansatz proposed by Fisher et al., [Phys. Rev. B 40, 546 (1989)], but they can all be reconciled within a phenomenological Ansatz in the presence of a dangerously irrelevant operator.

12 pages, 10 figures

References in corpus (12)

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• Cold atoms in the presence of disorder
• Bose glass and Mott glass of quasiparticles in a doped quantum magnet
• Phase Diagram of Commensurate Two-Dimensional Disordered Bose Hubbard Model
• A direct measurement of the Bose-Einstein Condensation universality class in NiCl${}_2$-4SC(NH${}_2$)${}_2$ at ultra-low temperatures
• Field-induced criticality in a gapped quantum magnet with bond disorder
• Low temperature thermodynamic properties near the field-induced quantum critical point in DTN
• Quantum Phase Transitions of Hard-Core Bosons in Background Potentials
• Quantum Critical Dynamics Simulation of Dirty Boson Systems
• Dirty Bosons: Twenty Years Later
• Magnetic Bose glass phases of coupled antiferromagnetic dimers with site dilution
• The disordered-free-moment phase: a low-field disordered state in spin-gap antiferromagnets with site dilution

Cited by in corpus (21)

• Bose glass and Mott glass of quasiparticles in a doped quantum magnet
• Dirty-boson physics with magnetic insulators
• Critical Exponents of the Superfluid-Bose Glass Transition in Three-Dimensions
• Quantum Critical Scaling of Dirty Bosons in Two Dimensions
• Criticality in a disordered quantum antiferromagnet by neutron diffraction
• Equilibrium phases of two-dimensional bosons in quasi-periodic lattices
• Detection of a Disorder-Induced Bose-Einstein Condensate in a Quantum Spin Material at High Magnetic Fields
• Criticality and Mott-glass phase in a disordered 2D quantum spin systems
• Disorder-induced Revival of the Bose-Einstein Condensation in Ni(Cl${}_{1-x}$Br${}_x$)${}_2$-4SC(NH${}_2$)${}_2$ at High Magnetic Fields
• Quantum Dynamics of Disordered Bosons in an Optical Lattice
• Quantum criticality in a three dimensional spin system at zero field and pressure
• Competing Bose-Glass physics with disorder-induced Bose-Einstein condensation in the doped $S=1$ antiferromagnet Ni(Cl${}_{1-x}$Br${}_x$)${}_2$-4SC(NH${}_2$)${}_2$ at high magnetic fields
• Stochastic approximation of dynamical exponent at quantum critical point
• Magnetically ordered phase near transition to Bose-glass phase
• Dirty bosons on the Cayley tree: Bose-Einstein condensation versus ergodicity breaking
• Spin waves near the edge of halogen substitution induced magnetic order in Ni(Cl${}_{1-x}$Br${}_x$)${}_2$$\cdot$4SC(NH${}_2$)${}_2$
• Quantum critical behavior of a three-dimensional superfluid-Mott glass transition
• Validity of Harris criterion for two-dimensional quantum spin systems with quenched disorder
• Quantum transition between magnetically ordered and Mott glass phases
• Numerical study of the temperature dependence of the NMR relaxation rate across the superfluid-Bose glass transition in one dimension
• Quantum-critical scaling at the Bose-glass transition of the 3d diluted Heisenberg antiferromagnet in a field