Manipulation of the magnetization in heavy-metal/ferromagnetic bilayers via the spin-orbit torque requires high spin Hall conductivity of the heavy metal. We measure inverse spin Hall voltage using a co-planar wave-guide based broadband ferromagnetic resonance set-up in Py/Ta system with varying crystalline phase of Ta. We demonstrate a strong correlation between the measured spin mixing conductance and spin Hall conductivity with the crystalline phase of Ta thin films. We found a large spin Hall conductivity of −2439 ( /e) Ω −1 cm −1 for low-resistivity (68 µΩ-cm) Ta film having mixed crystalline phase, which we attribute to an extrinsic mechanism of the spin Hall effect.

Spin-to-charge conversion is an essential requirement for the implementation of spintronic devices. Recently, monolayers of semiconducting transition metal dichalcogenides (TMDs) have attracted considerable interest for spin-to-charge conversion due to their high spin-orbit coupling and lack of inversion symmetry in their crystal structure. However, reports of direct measurement of spin-to-charge conversion at TMD-based interfaces are very much limited. Here, we report on the room temperature observation of a large spin-to-charge conversion arising from the interface of Ni80Fe20 (Py) and four distinct large area (∼ 5 × 2 mm 2 ) monolayer (ML) TMDs namely, MoS2, MoSe2, WS2, and WSe2. We show that both spin mixing conductance and the Rashba efficiency parameter (λIREE) scales with the spin-orbit coupling strength of the ML TMD layers. The λIREE parameter is found to range between −0.54 and −0.76 nm for the four monolayer TMDs, demonstrating a large spin-tocharge conversion. Our findings reveal that TMD/ferromagnet interface can be used for efficient generation and detection of spin current, opening new opportunities for novel spintronic devices.

Graphene/ferromagnet interface promises a plethora of new science and technology. The interfacial Dzyaloshinskii Moriya interaction (iDMI) is essential for stabilizing chiral spin textures, which are important for future spintronic devices. Here, we report direct observation of iDMI in graphene/Ni 80 Fe 20 /Ta heterostructure from non-reciprocity in spin-wave dispersion using Brillouin light scattering (BLS) technique. Linear scaling of iDMI with the inverse of Ni 80 Fe 20 thicknesses suggests primarily interfacial origin of iDMI. Both iDMI and spin-mixing conductance increase with the increase in defect density of graphene obtained by varying argon pressure during sputter deposition of Ni 80 Fe 20 . This suggests that the observed iDMI originates from defect-induced extrinsic spin-orbit coupling at the interface. The direct observation of iDMI at graphene/ferromagnet interface without perpendicular magnetic anisotropy opens new route in designing thin film heterostructures based on 2-D materials for controlling chiral spin structure such as skyrmions and bubbles, and magnetic domain-wallbased storage and memory devices.

The β phase of Ta is known to exhibit higher spin Hall efficiency compared to other heavy metals such as Pt. However, the larger resistivity of β-phase Ta leads to higher power consumption for spin–orbit torque (SOT)-based devices. In this work, we measure the efficiency of damping-like torque and field-like torque in Ni80Fe20/Ta using spin-torque ferromagnetic resonance technique. We report a larger damping-like torque efficiency of −(0.52 ± 0.01) for Ni80Fe20/Ta with low-resistive mixed (α + β)-phase Ta, which is about 40% larger compared to β-phase Ta. The field-like torque efficiency is found to be lower (by ≈400%) and of opposite sign compared to β-phase Ta. The estimated power consumption is found to be lower in the mixed-phase Ta system compared to the β-phase Ta as well as some Pt-based systems. Using micromagnetic simulations, we show that the measured values of damping-like torque and field-like torque for mixed-phase Ta lead to improved device performance, namely, (i) a lower switching time in a nanopillar-based SOT device and (ii) improved phase noise in a nanoconstriction-based spin Hall nano-oscillator.