Defect-related high temperature ferromagnetism in mechanically milled hexagonal boron nitride nanoplates

Abstract

We report a high Curie temperature ferromagnetism in milled hexagonal boron nitride (h-BN) nanoplates. The nanoplates with different sizes were synthesized via high-energy ball milling method. The magnetization versus magnetic field curves clearly indicate that the milled h-BN nanoplates exhibit distinct ferromagnetism, and their saturation magnetization increases monotonically from 0.015 to 0.032 emu/g with increasing of milling time at room temperature, while the bulk BN powders present diamagnetism. Besides, the temperature-dependent magnetization curve shows that the Curie temperature of the milled h-BN nanoplates is greater than 900 K. Meanwhile, Combined with the results of X-ray diffraction, high-resolution transmission electron microscope, X-ray photoelectron spectroscopy, Raman, and Electron spin resonance, the ferromagnetic behaviors of milled h-BN samples are attributed to nitrogen defects on the surface. Furthermore, the nitrogen defects on surface of h-BN can induce ferromagnetic states, which can be confirmed by the first principle calculation. The performance of high temperature ferromagnetism in h-BN material makes it promising candidates for application in spintronic devices.