Anomalous percolation and quantum criticality in diluted rare-earth nickelates

TL;DR

This study uses Quantum Monte Carlo simulations to explore how impurity concentration affects magnetic ordering and quantum criticality in diluted rare-earth nickelates, revealing universal behavior and potential quantum critical points.

Contribution

The paper introduces a microscopic model for diluted R_xY_(1-x)NiO_5 compounds and derives an effective model for critical modes, highlighting universal behavior and quantum criticality.

Findings

Ordering temperature depends universally on impurity concentration and chain correlation length.

Potential quantum critical point driven by rare earth concentration.

Existence of Griffiths phase at high dilution.

Abstract

A microscopic model for the diluted spin-mixed compounds (R_xY_(1-x))_2BaNiO_5 (R=magnetic rare-earth) is studied using Quantum Monte Carlo (QMC). The ordering temperature is shown to be a universal function of the impurity concentration x and the intrinsic Ni-chain correlation length. An effective model for the critical modes is derived. The possibility of a quantum critical point driven by the rare earth-concentration and the existence of a Griffiths phase in the high dilution limit is investigated. Several possible experimental approaches to verify the results are put forward.