F+ Center Exchange Mechanism and Magneto Crystalline Anisotropy in Ni doped 3C-SiC

TL;DR

This study provides experimental evidence of room temperature ferromagnetism in Ni-doped 3C-SiC, linking magnetic properties to F+ centers exchange mechanism and analyzing anisotropy variations with temperature.

Contribution

It demonstrates the role of F+ centers exchange mechanism in ferromagnetism and investigates magnetic anisotropy in Ni-doped 3C-SiC using various spectroscopic and structural techniques.

Findings

Curie temperature exceeds 350 K.

Ni exists as Ni2+ with specific environmental symmetry.

Effective magnetic anisotropic constant decreases with temperature.

Abstract

We report the experimental evidence in support of room temperature ferromagnetism in Ni doped 3C-SiC. Curie temperature is found to be > 350 K. Temperature dependent Electron paramagnetic resonance (EPR) study reveals that the valence state of Ni is 2+ and its environmental symmetry. A clear shift in both XRD and Raman peak confirms the incorporation of Ni in the host lattice. The variation in number of vacancies $V_{\mathrm{Si}}$, $V_{\mathrm{C}}$ and the number of free electron due to doping is consistent with the change in magnetization of the system. A direct correlation of ferromagnetic order (FM) with F+ centers exchange mechanism is established. The temperature variation of the anisotropic constant was determined using Law of Approach to Saturation (LAS). It was found that effective magnetic anisotropic constant decreases with increase in temperature. The EPR line width of the annealed sample increases with decrease in temperature, whereas the integrated intensity decreases with decrease in temperature. This could be due to incomplete quenching of orbital angular momentum in Si$_{x}$Ni$_{1-x}$C. In addition to this, the orbital degeneracy of fast relaxing impurity such as Ni in the cubic crystal field is not completely removed. This results in the line width decrease with increase in temperature.