Journal Article Vacancy-induced ferromagnetism in ZnO probed by spin-polarized positron annihilation spectroscopy

前川, 雅樹  ,  阿部, 浩之  ,  宮下, 敦巳  ,  境, 誠司  ,  山本, 春也  ,  河裾, 厚男

110 ( 17 )  , pp.172402-1 - 172402-5 , 2017-04 , AIP Publishing
We investigated ferromagnetism of ZnO induced by oxygen implantation using spin-polarized positron annihilation spectroscopy together with magnetization measurements. The magnetization measurements showed appearance of ferromagnetism after oxygen implantation and its disappearance during post-implantation annealing at above 573 K. The Doppler broadening of annihilation radiation (DBAR) spectrum showed asymmetry upon field reversal after the oxygen-implantation. The obtained differential DBAR spectrum between positive and negative magnetic fields was well-explained with a theoretical calculation considering zinc vacancies. The disappearance of field reversal asymmetry of DBAR spectrum by annealing agreed with that of ferromagnetism observed by magnetization measurements. These suggest that the radiation-induced zinc vacancies are the source for the observed ferromagnetism of ZnO.

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