Probing defect induced room temperature ferromagnetism in CVD grown MoO3 flakes: A correlation with electronic structure and first principle-based calculations

TL;DR

This study demonstrates that annealed MoO3 flakes grown via CVD exhibit room temperature ferromagnetism, which correlates with oxygen vacancies and is supported by first-principles calculations, revealing defect-induced magnetic properties.

Contribution

It provides new insights into defect-induced ferromagnetism in MoO3 flakes and links experimental magnetic behavior with electronic structure modifications due to oxygen vacancies.

Findings

All samples show room temperature ferromagnetism.

Maximum magnetic moment observed at 250°C annealing.

Oxygen vacancies correlate with increased magnetic moments.

Abstract

In this paper, we report the growth of pure {\alpha}-MoO3 micro-flakes by CVD technique and their structural, electronic, optical, and magnetic properties. Samples are annealed at various temperatures in an H2 atmosphere to induce ferromagnetism. All the samples exhibit ferromagnetism at room temperature, and 250oC annealed sample shows the highest magnetic moment of 0.087 emu/g. It is evident from PL data that pristine as well as annealed samples contain different types of defects like oxygen vacancies, surface defects, interstitial oxygen, etc. It is deduced from the analysis of Mo3d and O1s core-level XPS spectra that oxygen vacancies increase up to an annealing temperature of 250oC that correlates with the magnetic moment. Significant changes in the total density of states and also in the magnetic moment for two and three oxygen vacancies are noticed through first-principle-based calculations. It is concluded that the magnetic moment is produced by oxygen vacancies or vacancy clusters, which is consistent with our experimental findings.