Enhancement of magnetic moment in Zn_xFe_(3-x)O_4 thin films with dilute Zn substitution

摘要

Highly (111)-textured Zn_xFe_(3-x)O_4 thin films were grown by pulsed laser deposition on silicon substrates. The spin and orbital magnetic moments of the Zn_xFe_(3-x)O_4 thin films have been obtained by X-ray magnetic circular dichroism (XMCD) and sum rule analysis. The total magnetic moments thus extracted are in good agreement with the values obtained by vibrating sample magnetometer. Both the unquenched orbital moment and the ratio of orbital-to-spin moment first increase significantly with increasing Zn substitution at a low concentration range (0 ≤ x ≤ 0.1), and then decrease at a higher concentration (x = 0.3). The underlying site-specific doping mechanisms involved here have been elucidated by detailed analysis of the XMCD of Zn_xFe_(3-x)O_4 films. Our work demonstrates a practical means to manipulate the spin-orbit coupling in the Zn_xFe_(3-x)O_4 thin films via Zn impurity doping.