The dual effects of Al-doping on the ferromagnetism of Zn0.98–yEr0.02AlyO thin films

Hong-Ming Chen,Ze Xiong,Xue-Chao Liu,Shi-Yi Zhuo,Er-Wei Shi,Ren-Wei Zhou,Jian-Hua Yang

doi:10.1063/1.4819455

Hong-Ming Chen, Ze Xiong + Show 5 more

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https://doi.org/10.1063/1.4819455

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Abstract

Zn0.98–yEr0.02AlyO (0 ≤ y ≤ 0.04) thin films have been prepared by inductively coupled plasma enhanced physical vapor deposition method. It is found that Er3+ substitutes Zn2+ in ZnO lattice without forming any magnetic secondary phase. Al-doping has dual effects on the electron transport and magnetic properties of Er-doped ZnO films, wherein AlZn and Ali play different roles. When 0 ≤ y ≤ 0.02, the dominant AlZn increases and induces both carrier concentration and saturation magnetization (Ms) increasing. When 0.02 &lt; y ≤ 0.04, Ali becomes main defect and enhances the probability of electron scattering, thus reduces the Ms.

Highlights

There is tremendous flurry of research interest in diluted magnetic semiconductors (DMSs) for its potential application in spintronics.[1,2,3,4] It is because charge and spin of carriers can be simultaneously controlled in DMSs
For the Zn0.98–yEr0.02AlyO (0 ≤ y ≤ 0.04) thin films in this study, an obvious increase of c-axis length is observed in Fig. 1(b) after y > 0.02, which indicates that the ratio of Ali to AlZn may dramatically raise when the Al concentration is larger than 2 at.%
Room-temperature ferromagnetism has been obtained in Zn0.98–yEr0.02AlyO (0 ≤ y ≤ 0.04) thin films prepared by inductively coupled plasma enhanced physical vapor deposition (ICP-PVD) method

Summary

INTRODUCTION

There is tremendous flurry of research interest in diluted magnetic semiconductors (DMSs) for its potential application in spintronics.[1,2,3,4] It is because charge and spin of carriers can be simultaneously controlled in DMSs. Et al.[9,10] reported that Er-doped ZnO thin films exhibited room-temperature ferromagnetism and the ferromagnetism originated from Er substitution for Zn in ZnO lattice, while the effect of carrier concentration is not mentioned. Since Al-doping is able to increase carrier concentration in transition metals-doped ZnO, it is promising for modifying the magnetism. Some researchers have reported that Aldoping can increase the saturation magnetization (Ms) of Co-doped ZnO14,15 and Fe-doped ZnO16 due to the increase of carrier concentration. The role of Al-doping in the magnetism of Er-doped ZnO thin films still remains obscure. A series of experiments were designed to illustrate the ferromagnetism origin in the Er-doped ZnO system and to clarify the function of Al in Zn0.98–yEr0.02AlyO thin films

EXPERIMENT

RESULTS AND DISCUSSION

CONCLUSIONS