[25a-P01-1~51] 10 Spintronics and Magnetics (Poster)

English Presentation

[25a-P01-42] Origin of the difference in interfacial resistance between half-metallic Co₂FeGa_0.5Ge_0.5 and Co₂Mn_0.5Fe_0.5Si with the Ag spacer

〇(D)Kodchakorn SIMALAOTAO^1,2, Yoshio MIURA², Yuya SAKURABA^1,2 (1.Univ. of Tsukuba, 2.National Institute for Materials Science)

Keywords:

Current-perpendicular-to-plane giant magneto-resistive (CPP-GMR),First principles calculations,Interfacial resistance

Current-perpendicular-to-plane giant magneto-resistive (CPP-GMR) devices have been expected as a promising candidate for the next-generation magnetic read head in hard disk drives. Their small resistance area product is advantageous for compact read heads and high-speed reading. Co₂FeGa_0.5Ge_0.5(CFGG) and Co₂Mn_0.5Fe_0.5Si(CMFS) are two of the most representative half-metallic Co-based Heusler alloys which have experimentally showed the highest magnetoresistance (MR) in the CPP-GMR with Ag spacer^1,2. However, there is no comparative theoretical study to elucidate the difference of spin-dependent transport properties between CFGG and CMFS. In this study, we employed first principles calculations to calculate the majority-spin interface ballistic conductance, inversely proportional to the majority-spin interface resistance, for the (001)-CFGG/Ag/CFGG and CMFS/Ag/CMFS based on the Landauer formular. It was found that the majority-spin conductance of CFGG/Ag(001) interface was observed to be approximately 45% greater than that of CMFS/Ag(001) interface in all interfacial terminations, at its maximum difference, which indicates the advantage of CFGG to obtain large MR ratio in the CPP-GMR. The difference in the in-plane wave vector (k_||) dependence of the majority-spin conductance with three interfacial terminations (as depicted in Figure 1(a)-(c)) indicated a significantly conductive predominance of the CFGG electrode, particularly around the Brillouin zone (BZ) edge. These results suggested a higher MR output in CFGG/Ag/CFGG than CFMS/Ag/CFMS. Additionally, the analysis of Fermi surface matching revealed a clear overlap between the d states of CFGG electrode and p states of Ag spacer around the BZ edge.