Spin-to-charge conversion mediated by the inverse Rashba–Edelstein effect in polycrystalline thin films of the Weyl semimetal TaP

Abstract

Spintronics has attracted the attention of the scientific community for proving to be an efficient alternative to conventional electronics, and one of the most important issues is the study of spin current to charge current conversion. The diversity of materials for these studies makes the area more attractive. In this paper, we present experimental results of spin-to-charge conversion in polycrystalline sputtered films of the Weyl semimetal TaP, in which the spin currents are generated either by the spin pumping effect (SPE) produced by microwave-driven ferromagnetic resonance or by means of the spin Seebeck effect (SSE). The SPE studies were carried out with three types of structures: two with simple bilayers of TaP with either the ferrimagnetic insulator yttrium iron garnet (YIG-Y3Fe5O12) or the ferromagnetic metal permalloy (Py-Ni81Fe19), and one with trilayers of YIG/TaP/Py. Our results demonstrate that the spin-to-charge conversion in Weyl semimetal TaP thin films is due to the inverse Rashba–Edelstein effect (IREE) mechanism. The values of the IREE parameter measured by SPE are in the range λIREE = (0.63–1.15) pm, while the values measured by SSE are in the range λIREE = (0.80–0.96) pm. Thus, the two techniques yield consistent values for TaP films, which are comparable to the ones in graphene and some quantum materials, but are almost two orders of magnitude smaller than the one in bulk single-crystal TaP.