Quantum transport reveals spin glass correlations in a 2D network of TbPc$_{2}$ single-molecule magnets grafted on graphene

TL;DR

This study demonstrates that magnetic molecules on graphene induce 2D spin-glass correlations, revealed through magnetoresistance noise and conductance fluctuations, highlighting graphene's potential for exploring magnetic phase transitions.

Contribution

It provides experimental evidence of spin-glass correlations in graphene functionalized with magnetic molecules, a novel platform for studying 2D magnetic phase transitions.

Findings

Magnetoresistance exhibits magnetic field-dependent 1/f noise and universal conductance fluctuations.

Long-range 2D Ising spin-glass like correlations are induced in graphene.

Graphene with organic molecules can serve as a platform for magnetic phase transition studies.

Abstract

The low temperature magnetoresistance of graphene functionalized by an array of magnetic Terbium Phthalocyanines molecules is found to exhibit a magnetic field-dependent 1/f noise, along with universal conductance fluctuations (UCFs) typical of a mesoscopic phase-coherent sample. A thorough analysis of the magnetic field, temperature and chemical potential dependence of this 1/f noise and UCFs reveals that long range, 2D Ising spin-glass like, magnetic correlations are induced in graphene through exchange interactions between the magnetic molecules and charge carriers in graphene. These experiments show that graphene functionalized with organic molecules constitutes a versatile platform for the investigation of magnetic phase transitions in two dimensions.