Quantum localization in bilayer Heisenberg antiferromagnets with site dilution

TL;DR

This paper investigates how site dilution in bilayer Heisenberg antiferromagnets causes quantum localization of quasiparticles, leading to a Bose-glass phase and quantum disorder before classical percolation occurs.

Contribution

It demonstrates the emergence of a Bose-glass phase due to quantum localization caused by site dilution in a disordered bilayer Heisenberg model.

Findings

Quantum localization of quasiparticles due to site dilution.

Formation of an extended Bose-glass phase.

Quantum-disordered phase appears before classical percolation threshold.

Abstract

The field-induced antiferromagnetic ordering in systems of weakly coupled S=1/2 dimers at zero temperature can be described as a Bose-Einstein condensation of triplet quasiparticles (singlet quasiholes) in the ground state. For the case of a Heisenberg bilayer, it is here shown how the above picture is altered in the presence of site dilution of the magnetic lattice. Geometric randomness leads to quantum localization of the quasiparticles/quasiholes and to an extended Bose-glass phase in a realistic disordered model. This localization phenomenon drives the system towards a quantum-disordered phase well before the classical geometric percolation threshold is reached.