Experimental Evidence for Two-Dimensional Magnetic Order in Proton Bombarded Graphite

TL;DR

This study provides experimental evidence of two-dimensional magnetic order in proton-bombarded graphite, showing Curie temperatures above 350 K and spin wave excitations consistent with a 2D Heisenberg model.

Contribution

It demonstrates the induction of magnetic order in graphite via proton irradiation and characterizes the magnetic behavior as two-dimensional with high Curie temperatures.

Findings

Curie temperatures above 350 K in proton-bombarded graphite

Linear magnetization versus temperature indicating 2D spin wave excitations

Magnetic order stabilized at low irradiation fluences

Abstract

We have prepared magnetic graphite samples bombarded by protons at low temperatures and low fluences to attenuate the large thermal annealing produced during irradiation. An overall optimization of sample handling allowed us to find Curie temperatures $ T_c \gtrsim 350$ K at the used fluences. The magnetization versus temperature shows unequivocally a linear dependence, which can be interpreted as due to excitations of spin waves in a two dimensional Heisenberg model with a weak uniaxial anisotropy.