Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan.
WPI Advanced Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan.
Sci Rep. 2017 Jul 4;7(1):4576. doi: 10.1038/s41598-017-04901-4.
Spin pumping enables the generation of d.c. and gigahertz-band (GHz-band) voltages from an applied microwave via magnetization dynamics when combined with inverse spin Hall effects. However, generating such voltages in the in-between frequency region, or the megahertz (MHz) band, has been difficult since ferromagnetic resonance usually occurs in the GHz band. Here we show that in spite of GHz-band microwaves applied, MHz-band voltages can be generated by spin pumping with use of nonlinear magnetization dynamics in YFeO. The mechanism is ascribed to the MHz-band oscillation of the amplitude of the magnetization precession, which is projected onto a rectified voltage component via spin pumping. The present finding could be useful for frequency down-conversion thanks to the simple and durable structure, continuous-wave operation, and the tunability of an output frequency with low magnetic fields.
自旋泵浦通过与逆自旋霍尔效应结合，可在施加微波时通过磁化动力学产生直流和千兆赫兹（GHz）波段电压。然而，由于铁磁共振通常发生在 GHz 波段，因此在中频区或兆赫兹（MHz）波段产生这种电压一直很困难。在这里，我们展示了尽管施加了 GHz 波段的微波，但通过 YFeO 中的非线性磁化动力学，仍可以通过自旋泵浦产生 MHz 波段的电压。这种机制归因于通过自旋泵浦将磁化进动的幅度的 MHz 波段振荡投影到整流电压分量上。由于具有简单耐用的结构、连续波操作以及通过低磁场可调谐的输出频率，这一发现对于频率下变频可能很有用。
