Inverse Spin Hall Effect from pulsed Spin Current in Organic Semiconductors with Tunable Spin-Orbit Coupling

TL;DR

This paper demonstrates a pulsed ferromagnetic resonance method to significantly enhance the inverse spin Hall effect signals in organic semiconductors, enabling better spin-current detection and advancing spin-orbitronics in flexible materials.

Contribution

It introduces a pulsed excitation technique that amplifies ISHE signals in organic semiconductors, overcoming limitations of continuous-wave methods and broadening the scope of spintronics applications.

Findings

Pulsed FMR increases ISHE signals by 2-3 orders of magnitude.

Effective detection of spin currents in various organic semiconductors.

Potential for room-temperature spin-orbitronic devices.

Abstract

Exploration of spin-currents in organic semiconductors (OSECs) induced by resonant microwave absorption in ferromagnetic substrates has been of great interest for potential spintronics applications. Due to the inherently weak spin-orbit coupling (SOC) of OSECs, their inverse spin Hall effect (ISHE) response is very subtle; limited by the microwave power applicable under continuous-wave (cw) excitation. Here we introduce a novel approach for generating significant ISHE signals using pulsed ferromagnetic resonance, where the ISHE is ~2-3 orders of magnitude larger compared to cw excitation. This strong ISHE enables us to investigate a variety of OSECs ranging from pi-conjugated polymers with strong SOC that contain intrachain platinum atoms, to weak SOC polymers, to C60 films, where the SOC is predominantly caused by the molecule surface curvature. The pulsed-ISHE technique offers a robust route for efficient injection and detection schemes of spin-currents at room temperature, and paves the way for spin-orbitronics in plastic materials.