Stable high-temperature paramagnons in a three-dimensional antiferromagnet near quantum criticality: Application to TlCuCl${}_3$

Abstract

The complete set of hallmarks of the three-dimensional antiferromagnet near the quantum critical point has been recently observed in the spin dimer compound TlCuCl${}_3$. Nonetheless, the mechanism, responsible for several distinct features of the experimental data, has remained a puzzle, namely: (i) the paramagnons exhibit remarkable robustness to thermal damping and are stable up to high temperatures, where $k_{B}T$ is comparable with the excitation energy, (ii) the width to mass ratios of the high-temperature paramagnons are, within the error bars, equal to that of the low-temperature amplitude (or Higgs) mode. We propose such a mechanism and identify two principal factors, contributing to the scaling between width to mass ratios of the paramagnon and the amplitude mode: (i) the emergence of the thermal mass scale reorganizing the paramagnon decay processes, and (ii) substantial renormalization of the multi-magnon interactions by thermal fluctuations. The study is carried out for the general case of a $D=3+1$ quantum antiferromagnet within the framework of the ${\phi }^4$ model using the hybrid Callan-Symanzik + Wilson thermal renormalization group method. Our approach is tested by demonstrating a good quantitative agreement with available experimental data across the phase diagram of TlCuCl${}_3$.

References in corpus (6)

• Quantum Magnets under Pressure: Controlling Elementary Excitations in TlCuCl3
• Quantum and classical criticality in a dimerized quantum antiferromagnet
• Multiplicative logarithmic corrections to quantum criticality in three-dimensional dimerized antiferromagnets
• Asymptotic Freedom in Quantum Antiferromagnet TlCuCl3
• Non-equilibrium quantum mechanics: A 'hot quantum soup' of paramagnons
• Neutron spin-echo study of the critical dynamics of spin-5/2 antiferromagnets in two and three dimensions

Cited by in corpus (1)

• Unifying static and dynamic properties in 3D quantum antiferromagnets