Effect of anisotropic spin absorption on the Hanle effect in lateral spin valves

Abstract

We have succeeded in fully describing dynamic properties of spin current including the different spin absorption mechanism for longitudinal and transverse spins in lateral spin valves, which enables to elucidate intrinsic spin transport and relaxation mechanism in the nonmagnet.The deduced spin lifetimes are found independent of the contact type. From the transit-time distribution of spin current extracted from the Fourier transform in Hanle measurement data, the velocity of the spin current in Ag with Py/Ag Ohmic contact turns out much faster than that expected from the widely used model.

Effect of the interface resistance in non-local Hanle measurements

“…(2) with R NL from Ref. 8, we fixed all the parameters except for  Cu Hanle , which was left as the fitting parameter. This was done for the sake of simplicity, given the complexity of Eq.…”

“…1 (b)). Even though the values obtained from both methods should be identical, the validity of Hanle measurements in the case of transparent contacts has already been called into question [3,7,8,12]. …”

“…Whereas in the presence of a contact resistance both methods are in good agreement, we observe an anomalous behaviour for the case with transparent contacts, where there is a clear mismatch between both methods. While, for L larger than  N , this disagreement can be solved by taking into account the recently proposed spin absorption anisotropy at the FM electrodes [8], it is still present when L is shorter than  N , evidencing that an additional effect is influencing the spin precession.…”

“…Lateral spin valves (LSVs), consisting of two ferromagnetic (FM) electrodes bridged by a non-magnetic (NM) channel (see Fig. 1(a)), are widely used to electrically create pure spin currents due to their non-local geometry, in which a spinpolarized current is injected from one of the FM electrodes (the injector) into the NM channel, and the pure spin current at the second FM electrode (the detector) is measured [2][3][4][5][6][7][8][9][10][11][12][13][14][15].…”

“…The used model has also been widely discussed in terms of the liability of the obtained information. It has been suggested that it is not possible to measure Hanle effect with transparent interfaces [3,12] or that, if doing so, the equation needs to be carefully chosen [7,8].…”