Bias-dependent electrical spin generation in Fe3Si/GaAs : Consistent behavior in nonlocal and local spin valves and in the three-terminal configuration

Abstract

We study spin generation in lateral spin-valve structures consisting of ferromagnetic Fe 3 Si contacts on n-type GaAs transport channels. Different film-growth conditions are found to enable the comparison of ferromagnetic contacts with similar spin polarizations but different electrical characteristics. Strongly rectifying contacts are found to hinder the observation of spin-injection signals due to a strong bias dependence of the spin-generation efficiency. For contacts fabricated under optimized growth conditions, efficient spin generation enables the operation of nonlocal and local spin valves as well as the detection of spin signals in the three-terminal configuration. In all configurations, the observed signals exhibit a consistent bias-dependent spin generation and detection behavior which is explained by spin accumulation in the GaAs conduction band without the involvement of localized states.

Spin generation in completely MBE-grown Co2FeSi/MgO/GaAs lateral spin valves

“…3(b) well with previous data reported for similar GaAs transport channels. 9,21,38 Only for small strip distances L [ Fig. 3(a)], the finite width of the strip becomes relevant [cf.…”

“…9,56 On the other hand, under spin extraction conditions, the bias dependence of the SV signal directly reflects the spin-polarized electronic band structure of CFS. 9,59 For the sample with 4 ML MgO in Fig. 7(a), the sign of the spin signal ∆V SV changes at V int = 0.22 V. This sign reversal indicates the detection of the upper edge of the halfmetallic gap in L2 1 CFS which has been calculated to be around 0.3 eV.…”

“…For our analysis, we used the common assumption P gen = P det . 9,21,40 The parameters obtained by fitting the observed Hanle curves using Eq. 2 are given in Fig.…”

“…3,7 Regarding the FM/SC interface, the accurate design of the doping profile in the SC and the resulting electrical FM/SC contact characteristics are of major importance for efficient spin injection . 8,9 However, the epitaxial growth of CFS on top of a SC suffers from Fe and Co atoms diffusing into the SC, which not only compensate the doping profile, but also form magnetic impurities by which the spin polarized electrons are scattered. The loss of spin information consequently leads to a deterioration of spintronic functionalities.…”

The Degree‐of‐Order Dependent Electronic Structures and Magnetic Properties of Fe3Si Alloys

“…[19][20][21][22][23] Fe 3 Si can be considered as Heusler alloys: Fe[A,C] 2 Fe[B]Si with 45% spin polarization at Fermi level. [24] Therefore, Fe 3 Si is an attractive material for applications in these spintronic devices, such as Schottky-tunnel-barrier contacts for electrical injection and detection of spin polarized electrons, [25][26][27] spin valves, [28][29][30][31][32][33] and magnetic tunnel junctions. [34,35] However, highly ordered D0 3 -Fe 3 Si is easily subject to atomic disorder.…”