Observation of the Chiral Phonon Activated Spin Seebeck Effect

Utilization of the interaction between spin and heat currents is the central focus of the field of spin caloritronics. The recent emergence of chiral phonons possessing angular momentum arising from the broken symmetry of the lattice creates the potential for generating spin currents at room temperature in a non-magnetic material in response to a thermal gradient, precluding the need for a ferromagnetic contact. In this talk, we show the observation of spin currents generated by chiral phonons in a two-dimensional layered hybrid organic-inorganic perovskite implanted with chiral cations when subjected to a thermal gradient. Identified by transient magneto-optical Kerr effect measurements, the generated spin current shows a strong dependence on the chirality of the film and external magnetic fields, of which the coefficient is orders of magnitude larger than that produced by the reported spin Seebeck effect. Our findings indicate the potential of chiral phonons for spin caloritronic applications and offer a new route toward spin generation in the absence of magnetic materials.