Abstract
We have optimized the growth of superconducting TaN thin films on SiO2 substrates via dc magnetron sputtering and extract a maximum superconducting transition temperature of T c = 5 K as well as a maximum critical field μ 0 H c2 = (13.8 ± 0.1) T. This material is of interest for both different fields of quantum technology and superconducting spintronics as it represents a magnetic field-robust superconductor with strong spin–orbit interaction (SOI). After presenting the results of the growth optimization, we investigate in the second part the impact of the strong SOI in TaN on superconductor/ferromagnet heterostructures. To this end, we analyze the magnetization dynamics of both normal state and superconducting TaN/Ni80Fe20 (permalloy, Py)-bilayers as a function of temperature using broadband ferromagnetic resonance spectroscopy. In particular, we quantify the inverse current-induced torques of the bilayers and compare these results to NbN/Py-bilayers. In the normal state of TaN, we detect a positive damping-like current-induced torque σ d from the inverse spin Hall effect and a small field-like torque σ f attributed to the inverse Rashba–Edelstein effect at the TaN/Py-interface. In the superconducting state of TaN, we detect a negative σ d attributed to the quasiparticle mediated inverse spin Hall effect (QMiSHE) and the unexpected manifestation of a large positive field-like σ f of unknown origin matching our previous results for NbN/Py-bilayers. The QMiSHE can be used to probe spin currents in emergent quantum materials.
Highlights
Superconducting spintronics is a rapidly growing research field
That the purpose of this study is not to maximize Tc but to compare the spin-orbit torques arising from superconducting TaN to those that we previously reported for NbN32 grown on SiO2
In comparison to our results for NbN/Py-bilayers in Ref. 32, we find that the quasiparticle mediated inverse spin Hall effect (QMiSHE) is more pronounced in sample A (σd = −(1.2 ± 0.1) × 105/ Ωm at T /Tc ≈ 0.5), which we attribute to a larger spin Hall angle in TaN than in NbN due to spin-orbit interaction (SOI)
Summary
Superconducting spintronics is a rapidly growing research field. An important aspect is the investigation of methods for injecting angular momentum into superconducting materials to benefit from the potentially enhanced spin transport properties in superconductors[1,2,3,4,5]. First promising results include the detection of extremely long spin lifetimes[6] and large spin Hall angles (SHA)[7,8] in superconductors as well as the detection of enhanced spin transport properties in superconductor(SC)/ferromagnet(FM)-bilayers[9]. An emerging direction within this young field is the investigation of superconductors with large spin-orbit interaction (SOI)[10,11,12,13,14,15] or in proximity to heavy metals[9,16]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
