La_<0.7>Sr_<0.3>MnO_3トンネル接合のTMR特性(薄膜)

概要

論文の詳細を見る
Magnetic tunnel junctions using half-metallic La_<0.7>Sr_<0.3>MnO_3 (LSMO) were investigated. Two types of junctions, Co/SrTiO_3(STO)/LSMO (CSL junction) and LSMO/STO/LSMO (LSL junction) were prepared, where the Co layer on the STO layer of the CSL junction was grown at room temperature and the LSMO layer on the STO layer of the LSL junction was grown at 500℃ or 700℃. The observed TMR ratios for CSL and LSL junctions were 50% and -4%, respectively. The junction resistance of CSL increased exponentially with increasing STO thickness (t_<STO>), whereas that of LSL was almost independent of t_<STO>. It was found that the low TMR ratio of LSL was due to the inferior quality of the STO layer, caused during the growth of LSMO on the STO layer in an Ar atmosphere at high temperature. The inferiority of the STO layer-that is, introduction of defects into the STO layer- causes a decrease in the junction resistance and affects the decrease in the spin polarization of the upper LSMO layer, and subsequently results in the small TMR ratio.
社団法人日本磁気学会の論文
2004-04-01