Defect-induced magnetism in SiC probed by nuclear magnetic resonance

TL;DR

This study provides microscopic evidence of defect-induced bulk paramagnetism in SiC using NMR spectroscopy, revealing a Curie law temperature dependence and establishing a quantitative model for analyzing magnetic interactions.

Contribution

It introduces a microscopic NMR-based approach to analyze defect-induced magnetism in semiconductors, with a validated dipole-dipole interaction model.

Findings

NMR spectra follow a Curie law temperature dependence.

Good agreement between NMR data and dipole-dipole interaction model.

Method applicable to other materials for studying bulk magnetism.

Abstract

We give evidence for intrinsic, defect-induced bulk paramagnetism in SiC by means of $^{13}$C and $^{29}$Si nuclear magnetic resonance (NMR) spectroscopy. The temperature dependence of the internal dipole-field distribution, probed by the spin part of the NMR Knight shift and the spectral linewidth, follows a Curie law and scales very well with the macroscopic DC susceptibility. In order to quantitatively analyze the NMR spectra, a microscopic model based on dipole-dipole interactions was developed. The very good agreement between these simulations and the NMR data establishes a direct relation between the frequency distribution of the spectral intensity and the corresponding real-space volumes of nuclear spins. The presented approach by NMR can be applied to a variety of similar materials and, thus, opens a new avenue for the microscopic exploration and exploitation of diluted bulk magnetism in semiconductors.