Spin Current Volume Effect in Spin-lattice Coupled System

The magneto-volume effect (MVE), the volume change associated with spin fluctuation, has been a central issue in the physics of magnetism for a long time. Since the discovery of the MVE, extensive studies on the MVE have made remarkable progress in the physics of spin fluctuation and electronic correlation in ferromagnets. By contrast, recent spintronics studies have revealed that a spin current, a flow of spin angular momentum, is a powerful tool for controlling spin fluctuation, which should enable us to manipulate the volume of a magnet by using a spin current. In this chapter, we discuss the study on a volume modulation effect in a magnet by using a spin current. By injecting a spin current into a giant magnetostrictive material Tb \(_{0.3}\) Dy \(_{0.7}\) Fe \(_{2}\) , we demonstrated that a Tb \(_{0.3}\) Dy \(_{0.7}\) Fe \(_{2}\) film exhibits the thickness change in response to the spin current injection. By comparing the experimental results and the theoretical model, we found that the observed thickness change of the Tb \(_{0.3}\) Dy \(_{0.7}\) Fe \(_{2}\) film is attributed to the magnetization fluctuation change in the film induced by the spin current injection.