[22a-P09-1~14] 10 スピントロニクス・マグネティクス(ポスター)

▲ [22a-P09-7] Evaluation of resistivity in Ta-O/Co-Fe-B multilayers with the presence of interfacial scattering

〇Anh ThiVan Nguyen^1,2,3、Samik DuttaGupta^1,2,4、Yoshiaki Saito³、K. Vihanga De Zoysa^4,5、Shunsuke Fukami^1,2,3,4,5、Hiroshi Naganuma^1,2,3、Shoji Ikeda^1,2,3、Tetsuo Endoh^1,2,3,4,5、Yasushi Endo^1,2,5 (1.CSIS, Tohoku Univ.、2.CSRN, Tohoku Univ.、3.CIES, Tohoku Univ.、4.RIEC, Tohoku Univ.、5.ECEI, Tohoku Univ.)

キーワード：Resistivity evaluation, interfacial scattering, Sondheimer model

In the spintronic devices where the current flows in the layers’ plane, it is important to estimate the current flowing in each layer, which is widely calculated by macroscopic electrical engineering for parallel resistors based on the bulk resistivity of each layer. However, when the layer thickness becomes thinner than the mean free path of electrons, and/or in the system where the interfacial contribution is significant, this method leads to an over/underestimation of the current distribution due to the contribution of interface scattering to total resistivity of each layer [1]. Herein, we evaluate the total resistivity, including both bulk and interface contributions, for each layer of surface-treated Ta-O/Co-Fe-B multilayers by simply combining parallel resistors model with Sondheimer model [2].Ta-O (t_Ta-O)/Co-Fe-B(t_CFB)/MgO (1.3 nm)/Ta (1.0 nm) multilayers with various Ta-O layer thicknesses (t_Ta-O) and Co-Fe-B layer thicknesses (t_CFB) were fabricated by sputtering. Ta-O layer was formed by a surface treatment process of a Ta layer at different oxygen pressure (P_O2), which was confirmed by XAS. The sheet resistance (R_S) was measured by 4-probe method. At a fixed t_CFB, the relationship between R_S and t_Ta-O is expressed by the combination of the parallel resistors model and the Sondheimer model, where the bulk resistivity of the Ta-O layer and strength of interface scattering are taken into account. The total resistivity of Ta-O layer is estimated using bulk resistivity and strength of interface scattering. A similar method was used to estimate the resistivity of the Co-Fe-B layer. Figure 1 shows P_O2 dependence of total resistivity for Ta-O layer estimated using parallel resistors model combined with Sondheimer model, in comparison with those evaluated using the parallel resistors model. The total resistivity evaluated using the combined models increases with increasing P_O2, which is related to the increase of interfacial scattering in the system.