Among Cr-based sulfide spinels, CdCr2S4 and CuCr2S4 are well-established ferromagnetic semiconductor and ferromagnetic metal, respectively. Their solid solution, Cd(1-x)CuxCr2S4, in bulk form, has shown unique magnetic and transport properties that make them promising for the spintronic application. However, it remains challenging to obtain thin film of doped magnetic sulfide spinel materials for device usage. For the first time, we have attempted to synthesize Cd(1-x)CuxCr2S4 thin films using a versatile and straightforward chemical spray deposition (CSD) method combined with subsequent heat treatment in a sulfur atmosphere (sulfurization). A series of nanostructured Cd(1-x)CuxCr2S4 (x =0, 0.05, 0.1, 0.15, 0.2) thin films were grown from simple inorganic salts of Cd, Cu, and Cr. The X-ray diffraction analysis confirms the doped samples have the spinel structure with a spacegroup Fd3m. The replacement of Cd by Cu leads to a slight shift in the lattice parameter and Raman active vibration modes, exhibiting the lattice's structural changes with doping. X-ray photon emissions spectroscopy reveals Cu's bivalence and Cr's trivalence state in the Cd(1-x)CuxCr2S4 thin films. The optical bandgap in the visible region and magnetic transition temperature (Tc) shifts with Cu composition change. Moreover, spin-polarized calculations from first principles within GGA and PBE approximation have been performed to determine the electronic and magnetic structure in Cd(1-x)CuxCr2S4 and compared with experimental results.

Ferromagnetic Cd(1-x)CuxCr2S4 thin films: Synthesis, characterization and first-principles calculations

ACS Spring Meeting 2021

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