field-dependent XFMR fitting

Co-edge XFMR amplitude-vs-field and phase-vs-field data sets; MATLAB code for fitting (example: fit results shown in Fig. 4 in 10.1021/acs.nanolett.0c01868)Abstract of the associated publication (10.1021/acs.nanolett.0c01868) - Spin currents can exert spin-transfer torques on magnetic systems even in the limit of vanishingly small net magnetization, as recently shown for antiferromagnets. Here, we experimentally show that a spin-transfer torque is operative in a macroscopic ensemble of weakly interacting, randomly magnetized Co nanomagnets. We employ element- and time-resolved X-ray ferromagnetic resonance (XFMR) spectroscopy to directly detect subnanosecond dynamics of the Co nanomagnets, excited into precession with cone angle ≳0.003° by an oscillating spin current. XFMR measurements reveal that as the net moment of the ensemble decreases, the strength of the spin-transfer torque increases relative to those of magnetic field torques. Our findings point to spin-transfer torque as an effective way to manipulate the state of nanomagnet ensembles at subnanosecond time scales.

Co-edge XFMR幅值-场强和相位-场强数据集；用于拟合的MATLAB代码（例如：图4中展示了10.1021/acs.nanolett.0c01868的拟合结果）相关出版物摘要（10.1021/acs.nanolett.0c01868）：即使在网络磁化强度极小的极限情况下，自旋电流也能对磁性系统施加自旋传递扭矩，这一点最近在反铁磁体中得到了证实。在此，我们通过实验表明，在由弱相互作用的随机磁化Co纳米磁体组成的宏观集合中，自旋传递扭矩是有效的。我们采用元素和时分辨X射线铁磁共振（XFMR）光谱学，直接探测由振荡自旋电流激发到圆锥角≳0.003°进动的Co纳米磁体的亚纳秒动力学。XFMR测量显示，随着集合总磁矩的减小，与磁场扭矩相比，自旋传递扭矩的强度增加。我们的发现指出，自旋传递扭矩是操控亚纳秒时间尺度上纳米磁体集合状态的有效方法。