Experimental and Theoretical Validation of Room Temperature Intrinsic Ferromagnetism in Cr3C2 Due to Interstitial Carbon Atoms

Ferromagnetism is explored in Cr3C2 from microscopic to electronic levels and the spin coupling is attributed to the p electrons of the nearest-neighbor carbon atoms around the Cr-C atomic interactions. By using the spin-polarized density functional calculations, four models are formulated. The models reveal that the C atoms seated in tri-prism I site can induce magnetic moments and the C vacancies can also take part in the induced magnetic moment. The p-d orbital interactions between C interstitial atom and Cr atom contribute to two asymmetric states of majority and minority spins and lead to weak magnetic moments. The C interstitial atoms and C vacancies in the crystal lattice of Cr3C2 are observed by high-resolution transmission electron microscopy and electron-spin resonance (ESR) techniques. The magnetic properties of Cr3C2 are investigated by a superconducting quantum interference device.