Impurity spin texture at a deconfined quantum critical point

TL;DR

This paper investigates the impurity spin texture at a quantum critical point in antiferromagnets, revealing non-universal scaling behavior and providing insights into the nature of these unconventional phase transitions.

Contribution

It introduces a new quantum Monte Carlo method to analyze impurity effects and uncovers specific logarithmic deviations from expected universal scaling at the critical point.

Findings

Spin texture does not follow universal scaling at the critical point

Identifies logarithmic form of scaling violations

Provides clues for the theory of unconventional quantum phase transitions

Abstract

The spin texture surrounding a non-magnetic impurity in a quantum antiferromagnet is a sensitive probe of the novel physics of a class of quantum phase transitions between a Neel ordered phase and a valence bond solid phase in square lattice S=1/2 antiferromagnets. Using a newly developed T=0 Quantum Monte Carlo technique, we compute this spin texture at these transitions and find that it does not obey the universal scaling form expected at a scale invariant quantum critical point. We also identify the precise logarithmic form of these scaling violations. Our results are expected to yield important clues regarding the probable theory of these unconventional transitions.