Abstract
The control of ferromagnetism by light at room temperature is essential for the development of some optical-magnetic coupling devices, data storage and quantum computation techniques. In the present work, we demonstrate that the ferromagnetism of a semiconducting ZnO film on Pt substrate can be controlled by nonpolarized ultraviolet or violet light. The illumination of light with sufficiently high frequency photons could excite photogenerated electron-hole pairs in the semiconducting ZnO film. The amount of oxygen vacancies in the ZnO film and the appearance of built-in electric field due to the heterostructured ZnO/Pt may play important roles in the light-induced changes in the ferromagnetism of the ZnO film.
Highlights
On the other hand, room temperature ferromagnetism has been found in many pure semiconducting or insulating oxides containing nonmagnetic elements in the forms of thin films or nanograins[23,24,25,26,27,28,29]
In the present work, we find that the variation of ferromagnetism was not evident for Zinc oxide (ZnO) thin film annealed in an oxygen atmosphere, even at the illumination of ultraviolet light with λ= 365 nm, which is mainly ascribed to the lack of sufficient doubly ionized oxygen vacancy (Vo++) for the oxygen annealed ZnO
The magnetic field (H) dependence on the room temperature magnetization (M) after diamagnetism correction for the ZnO film as deposited on the substrate of Pt/Ti/SiO2/Si is shown in Fig. 2, where the magnetic field is applied parallel to the surface of the film
Summary
Jihao Xie[1], Hongwei Qin[1], Yanming Hao[2], Bin Cheng[1], Weikang Liu[1], Liang Liu[1], Shaoqing Ren[1], Guangjun Zhou[1], Ziwu Ji1 & Jifan Hu1. We demonstrate that the ferromagnetism of a semiconducting ZnO film on Pt substrate can be controlled by nonpolarized ultraviolet or violet light. The illumination of light with sufficiently high frequency photons could excite photogenerated electron-hole pairs in the semiconducting ZnO film. We demonstrate that the ferromagnetism of ZnO thin film on Pt substrate could be enhanced by nonpolarized ultraviolet or violet light at room temperature. We find that the ferromagnetism for ZnO thin film on MgO substrate under light illumination does not significantly change, which is mainly due to the ultrafast recombination of photogenerated electron-hole pairs with the absence of a built-in electric field. Our present work demonstrates a novel route to control the ferromagnetism of undoped semiconductors with nonpolarized light at room temperature
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