Weak-anti-localization-to-spin-dependent scattering at a proximity-magnetized heavy metal interface

Abstract

A change in a materials electrical resistance with magnetic field (magnetoresistance) results from quantum interference effects and, or spin-dependent transport, depending on materials properties and dimensionality. In disordered conductors, electron interference leads to weak localization or anti-localization; in contrast, ferromagnetic conductors support spin-dependent scattering, leading to giant magnetoresistance (GMR). By varying the thickness of Au between 4 and 28 nm in a EuS/Au/EuS spin-switches, we observe a crossover from weak anti-localization to interfacial GMR. The crossover is related to a magnetic proximity effect in Au due to electron scattering at the insulating EuS interface. The proximity-induced exchange field in Au suppresses weak anti-localization, consistent with Maekawa-Fukuyama theory. With increasing Au thickness, GMR emerges along with spin Hall magnetoresistance. These findings demonstrate spin transport governed by interfacial exchange fields, building a framework for spintronic functionality without metallic magnetism.

Figures (4)

• Figure 1: (a) Normalized resistance ($R(T)-R_{\mathrm {min}})/R_{\mathrm {min}}$ in zero field cooling vs. temperature ($T$) for EuS(20 nm)/ Au($d$)/EuS(10 nm) and Au(7 nm)/STO control structures. Inset: normalized increase of resistance ($\Delta R$) vs. $d$ at 3 K for spin-switches (circles) and control structures (triangle). (b) $(R(T)-R_{\mathrm {min}})/R_{\mathrm {min}}$ in zero-field cooling vs. $T$ for the control structure. (c) Schematic illustrations of the cross-section of the spin-switch and control structure in (a) and (b).
• Figure 2: (a) In-plane $M(H)$ for an unpatterned EuS(20 nm)/ Au(16 nm)/EuS(10 nm) structure at 3 K. (b-c) In-plane $R(H)$ of unpatterned EuS(20 nm)/Au($d$)/EuS(10 nm) structures at 3 K. (b): $d=$ 4 nm; (c): $d=$ 6 to 28 nm. Shaded areas indicate AP magnetizations estimated from $M(H)$
• Figure 3: In-plane MR vs. $T$ (a) and vs. $d$ (b) for EuS(20 nm)/Au($d$)/EuS(10 nm). The dotted lines in (a) are fits to Maekawa-Fukuyama theory in the WLR and solid line fits in (b) include a phenomenological effect from WLR and interfacial GMR (see Supplemental Material Part IV in ref supplement_2025).
• Figure 4: (a) Out-of-plane $M(H)$ for an unpatterned EuS(20 nm)/Au($d$)/EuS(10 nm) structure with $d$ = 16 nm at 2 K. Inset: $M(H)$ over a smaller field range. (b) Anomalous Hall resistivity of EuS(20 nm)/Au($d$)/EuS(10 nm) with $d$ = 4, 8 and 16 nm Hall bar structures at 2 K.