Wang Hanchen, Kang Min-Gu, Petrosyan Davit, Ding Shilei, Schlitz Richard, Riddiford Lauren J, Legrand William, Gambardella Pietro
ETH Zurich, Laboratory for Magnetism and Interface Physics, Department of Materials, Zurich 8093, Switzerland.
ETH Zurich, Laboratory for Mesoscopic Systems, Department of Materials, 8093, Zurich, Switzerland.
Phys Rev Lett. 2025 Mar 28;134(12):126701. doi: 10.1103/PhysRevLett.134.126701.
We report the detection of pure orbital currents generated by both coherent and thermal magnons in the magnetic insulator Bi-doped yttrium iron garnet (BiYIG). The pumping of orbital and spin currents is jointly investigated in nanodevices made of naturally oxidized Cu, pure Cu, Pt, and Cr. The absence of charge conduction in BiYIG and the negligible spin-to-charge conversion of oxidized Cu allows us to disambiguate the orbital current contribution. Comparative measurements on YIG and BiYIG show that the origin of the orbital pumping in BiYIG/oxidized Cu is the dynamics of the orbital magnetization in the magnetic insulator. In Cr, the pumping signal is dominated by the negative spin Hall effect rather than the positive orbital Hall effect, indicating that orbital currents represent a minority of the total angular momentum current pumped from the magnetic insulator. Our results also evidence that improving the interfacial transparency significantly enhances pumping efficiencies, not only for spin but also for orbital currents.
我们报告了在磁性绝缘体铋掺杂钇铁石榴石（BiYIG）中由相干和热磁振子产生的纯轨道电流的检测结果。在由自然氧化的铜、纯铜、铂和铬制成的纳米器件中，对轨道电流和自旋电流的泵浦进行了联合研究。BiYIG中不存在电荷传导，且氧化铜的自旋到电荷转换可忽略不计，这使我们能够明确轨道电流的贡献。对YIG和BiYIG的对比测量表明，BiYIG/氧化铜中轨道泵浦的起源是磁性绝缘体中轨道磁化的动力学。在铬中，泵浦信号主要由负自旋霍尔效应而非正轨道霍尔效应主导，这表明轨道电流在从磁性绝缘体泵浦的总角动量电流中占少数。我们的结果还证明，提高界面透明度不仅能显著提高自旋电流的泵浦效率，也能提高轨道电流的泵浦效率。
