Quantum phase transitions and dimensional reduction in antiferromagnets with inter-layer frustration

TL;DR

This paper investigates quantum phase transitions in frustrated antiferromagnets, revealing a crossover from two-dimensional to three-dimensional behavior driven by weak inter-layer couplings, with implications for experimental observations.

Contribution

It demonstrates that quantum phase transitions in frustrated layered antiferromagnets are effectively three-dimensional at low temperatures due to interaction-generated couplings, despite initial frustration.

Findings

Quantum phase transitions are asymptotically 3D due to non-frustrated couplings.

A tiny crossover scale leads to 2D behavior in low-temperature regimes.

Pressure can induce a split transition breaking Ising symmetry before magnetism.

Abstract

For magnets with a fully frustrated inter-layer interaction, we argue that the quantum phase transitions from a paramagnetic to an antiferromagnetic ground state, driven by pressure or magnetic field, are asymptotically three-dimensional, due to interaction-generated non-frustrated inter-layer couplings. However, the relevant crossover scale is tiny, such that two-dimensional behavior occurs in an experimentally relevant low-temperature regime. In the pressure-driven case the phase transition may split, in which case an Ising symmetry related to inter-layer bond order is broken before magnetism occurs. We discuss the relation of our results to recent experiments on BaCuSi2O6.