ホイスラー合金層を用いた多結晶面直電流型巨大磁気抵抗素子の高出力化

针对CPP-MR这一主题，我们研制了一种以Mg-Ti-O(MTO)为基础的三层间隔层，并利用它在CPP-MR器件中获得了较大的MR输出。具体地说，使用Ag/MTO/Ag三层间隔层，我们的CPP-MR器件获得了大于10 mV的大的增量Vmax(最高可达16 mV)，RA为200-300mΩμm2。对于自旋电流的产生，我们研究了具有新型导电NM层的非磁/铁磁(NM/FM)双层膜的自旋霍尔磁电阻(SMR)。结果，在这样的双层堆栈中观察到了相当大的SMR比，这与在具有诸如铂的贵金属的NM的堆栈中观察到的SMR大小相当。这种SMR的产生可能与NM层的大的自旋-轨道耦合或NM/FM界面的Rashba-Edelstein效应有关。另一方面，我们研究了NM1/FM/NM2三层堆栈中的SMR，以考察第二界面如何影响此类系统的整体自旋轨道扭矩(SOTS)。结果发现，SOTS与FM层和NM2层的自旋扩散长度密切相关，特别是与FM/NM2界面的自旋输运透明度有关。通过计算系统各自的有效自旋混合电导，我们定量地评价了这种系统中的类阻尼型和类场SOTS，为控制NM/FM界面上的SOTS提供了有用的信息。

For the topic of CPP-MR, we have developed a Mg-Ti-O (MTO)-based tri-layer spacer and obtained large MR output in CPP-MR devices using it. Specifically, with a tri-layer spacer of Ag/MTO/Ag, large delta-Vmax over 10 mV is obtained (highest of 16 mV) in our CPP-MR devices with RA of 200-300 mΩ μm2. We find that the large MR output is very likely to originate from the formation of metallic Ag channels penetrating the MTO layer.For the topic of spin current generation, we have studied the spin Hall magnetoresistance (SMR) in non-magnetic/ferromagnetic (NM/FM) bilayer with novel conductive NM layer. As a result, considerable SMR ratio has been observed in such a bilayer stack, which is comparable to the SMR magnitude observed in stacks with NM being a noble metal such as Pt. The origin of such a SMR can be related to the large spin-orbit coupling in the NM layer or the Rashba-Edelstein effect at the NM/FM interfaces. On the other hand, we have studied the SMR in NM1/FM/NM2 tri-layer stack to investigate how a second interface affects the overall spin-orbit torques (SOTs) in such a system. As a result, we have found that the SOTs are strongly related to the spin diffusion length of FM layer and NM2 layer placed upon it, and specifically, related to the spin transport transparency at the FM/NM2 interfaces. By calculating the respective effective spin mixing conductance of the systems, we quantitatively evaluate the damping-like and field-like SOTs in such a system, providing useful information to the control of SOTs at NM/FM interfaces.