Spin-to-Charge Conversion in Spin Hall Effect Materials, Rashba Interfaces, and Topological Insulators

Orateur : Yu FU (INAC Grenoble)

Several materials, ranging from bulk materials to 2D electron gas at Rashba or topological insulator interfaces, have r ecently been shown to allow the transformation of charge currents into pure spin currents. The discovery of this property is the basis of a new research topic, spinorbitronics, which aims particularly at understanding how spin-orbit interaction can be used to control magnetization. The manipulation of those pure spin currents, which correspond to a flow of angular momentum without net charge flow, can indeed be used to induce magnetic precession or magnetization switching. This allows foreseeing numbers of spintronics memory and logic applications, and opens new fundamental challenges for the condensed-matter community. This seminar will focus on a method for studying the spin to charge conversion, named spin pumping. The principle is to use ferromagnetic material deposited on top of a spin-orbit material. When exciting the ferromagnet at the ferromagnetic resonance, the magnetization precession in the ferromagnet injects a pure spin current into the spin-orbit material. The injected spin current is then converted into a transverse charge current, via Inverse Spin Hall Effect in heavy metals/ alloys [1], or via Inverse Edelstein Effect at Rashba interfaces [2] or topological insulator interfaces [3]. We will show that we could obtain efficient spin-to-charge conversions by using metallic alloy spin Hall effect materials which will be compared to pure elements like Pt [1,4], and using the 2D electron gas at Rashba interface [2] and topological insulators [3].

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