Investigation of interfacial spin transport in chiral RhSi epitaxial thin films

The rise of nonmagnetic chiral topological semimetals as a uniquely attractive playground for the observation and control of various spin-orbit effects has ushered in the promising field of topological spintronics. RhSi, a spin-1 chiral semimetal with a noncentrosymmetric cubic B20 structure, has attracted attention as it accommodates unconventional multifold fermions that extends our understanding beyond common Dirac and Weyl fermions. In this work, we have investigated the spin-to-charge interconversion through spin pumping and inverse-spin Hall effect(ISHE) in sputter-grown epitaxial RhSi thin films and its subsequent transport across RhSi/Py interface. From the observed modulation of Gilbert damping parameter and ISHE voltage with RhSi thickness, the spin-Hall angle of RhSi and interfacial spin transparency of RhSi/Permalloy interface is determined. A stark variation of spin Hall angle and interfacial spin transparency is observed with ambient temperature in this heterostructure. The spin Hall angle and spin Hall conductivity is found to be maximum of 1.42% and 251.64, respectively. A spin-mixing conductance and interfacial spin transparency as high as 34.7 nm^-2 and 88% is attainable in these heterostructures. This study expands the horizon of topological spintronics and highlights the controlled spin-charge interconversion and interfacial spin-transport process in a chiral semimetal/ferromagnet heterostructure which can be beneficial for the development of chiraltronics and spin-orbitronics devices.