Effect of Cr-substitution on vanadium dioxide thin films studied by soft X-ray magnetic circular dichroism

Abstract

The tunability of magnetic properties of VO 2 has fascinated substantial attention in the first generation of spintronics-related applications such as read head sensors for hard disk drives and magnetic random-access memory. In this work, we focus on Cr doped VO 2 , V 1− x Cr x O 2 (0 ≤ x ≤ 0 . 3) (VCO) thin films and study the effect of Cr-substitution on the structural, electronic and magnetic properties. The VCO films were deposited on R-sapphire substrates using a pulse laser deposition method. Soft X-ray absorption spectroscopy (XAS) and soft X-ray magnetic circular dichroism (XMCD) studies of VCO thin films were performed to reveal and understand the origin of maTablegnetization and their enhancement with Cr-substitution. The XAS spectra suggest that the valences of V ions are in tetra and pentavalent states and Cr ions in the trivalent state. The XMCD spectra imply that the V and Cr ions are ferromagnetic at room temperature. These results also indicate that the VCO films are in the ferromagnetic insulating state and charge-ordered at the V and Cr sites. These results are consistent with the first principle density functional theory calculations. • XRD results suggest that a gradual structural change from the monoclinic M1 phase (0 ≤ x < 0.05) to triclinic T phase (0.05 ≤ x ≤ 0.20 to monoclinic M2 phase ( x > 0.20). • First Study to understand the origin of magnetization. • The VCO films are in the ferromagnetic insulating state and charge-ordered at the V and Cr sites, consistent with DFT. • The XMCD spectra indicate that the V and Cr ions are ferromagnetic at room temperature.