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

Most people involved in TOPTRONICS
News and events

– The Toptronics’ PI co-organized the International Workshop in Spintronics Spin Argentina to be held in Bariloche, Argentina Nov 6th -11th , 2022.

– The Toptronics’ PI, Carlos ROJAS, just got an invitation to give at talk at the prestigious APS March Meeting 2022. He was asked to talk about self-torque in GdFeCo ! Our work just published in Advanced Materials.

– We have two accepted contribute talks at next 2022 Joint MMM-Intermag in New Orleans! One by Alberto Anadon and the other one by Victor Palin.

– We have just been invited to submit an article at the Physica Status Solidi (RRL) for its special edition for its 60th anniversary. Invitation that we have gladly accepted (10/2021).

– Héloïse Damas got an invitation at the International Lorraine-Tohoku Workshop (January 2021). She also got a contributed talk at Intermag 2021, a talk at 2021 ESpinRed School on Spintronics, a talk at the IEEE Magnetic Society Around-the-Clock Around-the-Globe 2021. She was accepted to participate and attended the European School in Magnetism EMA 2021.

– Carlos Rojas was invited to give several online talks or seminars this 2021. He also got an invited talk at Trends in Magnetism Conference TMAG2020 which was held in Cefalu (Italy) from 6 to 10 September 2021.

– The Toptronics’ PI was invited to submit an article for special issue of APL Materials. Our open access invited paper is online now!


CurrentInduced Spin Torques on Single GdFeCo Magnetic Layers. David CéspedesBerrocal, Heloïse Damas, Sébastien PetitWatelot*, Davide Maccariello, Ping Tang, Aldo ArriolaCórdova, Pierre Vallobra, Yong Xu, JeanLoïs Bello, Elodie Martin, Sylvie Migot, Jaafar Ghanbaja, Shufeng Zhang, Michel Hehn, Stéphane Mangin, Christos Panagopoulos, Vincent Cros, Albert Fert*, JuanCarlos RojasSánchez*. Advanced Materials 33, 2007047 (2021). https://doi.org/10.1002/adma.202007047


Engineering the spin conversion in graphene monolayer epitaxial structures. Alberto Anadón, Adrián Gudín, Rubén Guerrero, Iciar Arnay, Alejandra Guedeja-Marron, Pilar Jiménez-Cavero, Jose Manuel Díez Toledano, Fernando Ajejas, María Varela, Sebastien Petit-Watelot, Irene Lucas, Luis Morellón, Pedro Antonio Algarabel, Manuel Ricardo Ibarra, Rodolfo Miranda, Julio Camarero, Juan-Carlos Rojas-Sánchez, Paolo Perna. APL Materials 9, 061113 (2021). https://doi.org/10.1063/5.0048612


Determination of spin Hall angle, spin mixing conductance, and spin diffusion length in CoFeB/Ir for spin-orbitronic devices. T Fache, JC Rojas-Sanchez*, L Badie, S Mangin, S Petit-Watelot*. Physical Review B 102, 064425 (2020). https://doi.org/10.1103/PhysRevB.102.064425