Revealing Novel Quantum Phases in Quantum Antiferromagnets on Random Lattices

TL;DR

This paper reviews how geometric randomness and quantum fluctuations in disordered quantum magnets lead to novel quantum phases and alter phase transition universality classes, revealing quantum Griffiths and Bose glass phases.

Contribution

It introduces the impact of disorder on quantum phase transitions, highlighting the emergence of inhomogeneous phases and quantum percolative transitions in quantum antiferromagnets.

Findings

Disorder changes the universality class of phase transitions.

Emergence of quantum Griffiths and Bose glass phases.

Inhomogeneity leads to quantum percolative transitions.

Abstract

Quantum magnets represent an ideal playground for the controlled realization of novel quantum phases and of quantum phase transitions. The Hamiltonian of the system can be indeed manipulated by applying a magnetic field or pressure on the sample. When doping the system with non-magnetic impurities, novel inhomogeneous phases emerge from the interplay between geometric randomness and quantum fluctuations. In this paper we review our recent work on quantum phase transitions and novel quantum phases realized in disordered quantum magnets. The system inhomogeneity is found to strongly affect phase transitions by changing their universality class, giving the transition a novel, quantum percolative nature. Such transitions connect conventionally ordered phases to unconventional, quantum disordered ones - quantum Griffiths phases, magnetic Bose glass phases - exhibiting gapless spectra associated with low-energy localized excitations.