Possible Origin of Ferromagnetism in an Undoped ZnO d0 Semiconductor

Abstract

First-principles calculations were employed to investigate the effect of native defects and a hydrogen-related defect complex on ferromagnetism in an undoped ZnO semiconductor. The results show that the zinc vacancy (V Zn ) could lead to a moment of 1.73 μB in the undoped ZnO supercell, while the oxygen vacancy could not, but the formation energy of the zinc vacancy is much higher than that of the oxygen vacancy. When the hydrogen atom is doped in imperfect ZnO, the formation energy of V Zn +H I sharply decreases, compared with that of V Zn . Meanwhile, the V Zn +H I defect complex can induce a 0.99(0.65) μB moment in the Zn 15 H I O 16 supercell. Furthermore, the total energy of the ZnO supercell with two defect complexes for the ferromagnetic phase is lower than that for the antiferromagnetic phase, and the calculated results show that a strong magnetic coupling exists in the ferromagnetic phase. As an unintentionally doped element, H usually appears in ZnO prepared by many methods. So the ferromagnetism in the ZnO d0 semiconductor most probably arises from the defect complex of the zinc vacancy and H.

Observation of the origin of d0magnetism in ZnO nanostructures using X-ray-based microscopic and spectroscopic techniques

“…Keavney et al 21 have used the Cu, Zn L 3,2 -and O Kedge X-ray magnetic circular dichroism (XMCD) techniques and found no XMCD signal in a Cu-doped ZnO thin lm. [24][25][26][27][28][29] Specically, Wang et al 24 have utilized density functional theory (DFT) calculations to demonstrate the role of V Zn , which induces spin polarization at the top of the valence band in d 0 magnetism. Chaboy et al 22 have veried the role of the conduction band in the magnetism and have ruled out the possibility of a valence band (basically, Zn 3d orbitals) in thiol-capped ZnO nanoparticles by performing a Zn K-edge XMCD measurement.…”

Enhanced ferromagnetism of ZnO@Co/Ni hybrid core@shell nanowires grown by electrochemical deposition method

“…Meanwhile, the intrinsic ferromagnetism of bare ZnO NWs is also an interesting feature which has been studied by several research groups recently, and is promising for many applications of nanoscaled optomagnetics, optoelectronics devices, and biotechnology. [35][36][37][38] Moreover, the synthesis of such hybrid core@shell structure still remains challenging and time-consuming. Therefore, we considered investigating the enhanced ferromagnetism of ZnO NWs by coating with nanolayers of giant positive magnetic Co and Ni materials through a facile synthetic process.…”

Effect of Intrinsic Point Defect on the Magnetic Properties of ZnO Nanowire

“…Recently diluted magnetic semiconductors (DMSs) have attracted much attention due to their potential application in novel spintronic devices. Among these DMSs, low dimensional ZnO-based DMSs have been found to be promising for nanometer scale optomagnetics devices, optoelectronics devices, and biotechnology [ 1 – 15 ]. Many investigations have been reported regarding the intrinsic ferromagnetism in undoped one-dimensional ZnO nanomaterials [ 9 – 15 ].…”