Puebla Jorge, Auvray Florent, Yamaguchi Naoya, Xu Mingran, Bisri Satria Zulkarnaen, Iwasa Yoshihiro, Ishii Fumiyuki, Otani Yoshichika
CEMS, RIKEN, Saitama, 351-0198, Japan.
Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8581, Japan.
Phys Rev Lett. 2019 Jun 28;122(25):256401. doi: 10.1103/PhysRevLett.122.256401.
At interfaces with inversion symmetry breaking, the Rashba effect couples the motion of the electrons to their spin; as a result, a spin charge interconversion mechanism can occur. These interconversion mechanisms commonly exploit Rashba spin splitting at the Fermi level by spin pumping or spin torque ferromagnetic resonance. Here, we report evidence of significant photoinduced spin-to-charge conversion via Rashba spin splitting in an unoccupied state above the Fermi level at the Cu(111)/α-Bi_{2}O_{3} interface. We predict an average Rashba coefficient of 1.72×10^{-10} eV m at 1.98 eV above the Fermi level, by a fully relativistic first principles analysis of the interfacial electronic structure with spin orbit interaction. We find agreement with our observation of helicity dependent photoinduced spin-to-charge conversion excited at 1.96 eV at room temperature, with a spin current generation of J_{s}=10^{6} A/m^{2}. The present Letter shows evidence of efficient spin charge conversion exploiting Rashba spin splitting at excited states, harvesting light energy without magnetic materials or external magnetic fields.
在具有反演对称性破缺的界面处， Rashba效应将电子的运动与其自旋耦合； 因此， 可以发生自旋电荷相互转换机制。 这些相互转换机制通常通过自旋泵浦或自旋扭矩铁磁共振利用费米能级处的Rashba自旋分裂。 在此， 我们报告了在Cu(111)/α - Bi₂O₃界面上高于费米能级的未占据状态下， 通过Rashba自旋分裂实现显著光致自旋到电荷转换的证据。 通过对具有自旋轨道相互作用的界面电子结构进行完全相对论性第一性原理分析， 我们预测在高于费米能级1.98 eV处的平均Rashba系数为1.72×10⁻¹⁰ eV·m。 我们发现与我们在室温下对1.96 eV激发的螺旋度相关光致自旋到电荷转换的观察结果一致， 自旋电流产生为Js = 10⁶ A/m²。 本信函展示了利用激发态的Rashba自旋分裂实现高效自旋电荷转换的证据， 无需磁性材料或外部磁场即可收集光能。
