||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
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.