With TOPTRONIC, we want to explore new paradigms using spin-charge current conversion by spin-momentum locking at interface states of topological insulators



Topological spin-orbitronics

Image caption: (a) Illustration of the linear relationship of the surface or topological states of a topological insulator (TI) with its spin texture due to its spin-momentum locking. (b) A temperature gradient T can generate a spin current in the ferromagnetic HA layer which in turn could be converted into an output voltage V, due to the expected high spin-charge conversion efficiency on the topological states. The combination of these effects can be used for harvesting energy. (c) Materials that have spin texture as in TI or two-dimensional systems (2DEG) can efficiently generate a Js spin current, which can then be used to manipulate the magnetization M of a ferromagnetic (FM) layer. These effects can be used in applications such as magnetic memory and logic circuits.

Summary: Conversions between spin and charge currents by Spin-Orbit effects begin to be used in spintronic devices such as Spin-Orbit Magnetic Memories (SOT-MRAMs) harnessing the Spin Hall Effect of heavy metals such as Pt. We want to explore new paradigms in this field using spin-charge current conversion by spin-momentum locking at interface states of topological insulators (TIs) such as a-Sn and half-Heusler alloys, integrated with non-classical magnetic materials such as Heusler alloys (HA). This goal is strongly coupled to the objective of using the spin-charge current conversions in different types of devices including power generators for the transformation of heat flow into electrical power thanks to new spin-thermal effects where a temperature gradient generates a spin current, namely spin Seebeck effect and spin Nernst effect.

Members:  The scientific members includes all members of the SPIN team, explicitly Dr. Juan-Carlos Rojas-Sánchez (PI), Prof. Stephan Andrieu (specialist in MBE), Prof. François Montaigne (optical and e-beam lithography, former Head of cleanroom facilities, magnetotransport); Dr. Sébastien Petit-Watelot ( ultra-low noise magneto-transport at low and high frequencies, and FMR); Dr. Olivier Copie ( oxides and PLD); and Prof. Michel Hehn ( Magnetic tunnel junction, ferrimagnets and sputtering); as well as Prof. Yannick Fagot-Révurat (ARPES and scanning tunnel microcopy)

Funding: 256 k€

Scientific project timeline:  01/04/2020 – 31/03/2023


Institut Jean Lamour (IJL) (Nancy, France)

External collaborators

Prof. Albert Fert (UMPhi CNRS-Thales)

Dr. Yoshiyuki Ohtsubo (Osaka University, Japan)

We are open to collaboration with colleagues from all over the world