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Paul NOËL, winner of the 2020 Academic Thesis Award

Paul Noël is the winner of the Academic Thesis Award 2020 with 7 other PhDs for his thesis presented in 2019 and entitled "Dynamical spin injection and spin to charge current conversion in oxide-based Rashba interfaces and topological insulators". The academic thesis prizes were awarded to eight Doctors using criteria of excellence specific to each discipline and represented by the 13 doctoral schools on site.
Winner of the 2020 Academic Thesis Award: Paul NOËL

Paul NOËL, lauréat du prix de thèse académique 2020Thesis title: Dynamical spin injection and spin to charge current conversion in oxide-based Rashba interfaces and topological insulators.

Doctoral school: ED Physics

Host laboratory: SPINTEC - IRIG (CEA / CNRS / UGA / Grenoble INP-UGA)

Thesis supervisor: Jean-Philippe ATTANE (Laurent VILA, co-supervisor)

Key words: spintronics, spinorbitronics, spin current, spin hall effect, Rashba effect, topological insulators

The thesis focuses on a detailed study of spin/charge conversion in several systems, including oxide interfaces and topological insulators. This thesis was carried out on an innovative subject at the crossroads of fundamental physics and new technologies for storing information in magnetic memories and requires a thorough command of the most advanced techniques of magnetism but also those of nanofabrication for the preparation of samples.

Abstract

Using a ferromagnetic layer has been the first method to obtain and detect spin currents, allowing to modify the magnetization state of an adjacent layer using spin transfer torque. However, in recent years, an alternative way to manipulate spin currents has been proposed. An emerging field of spintronics, called spin-orbitronics, exploits the interplay between charge and spin currents enabled by the spin-orbit coupling (SOC) in non-magnetic systems. An efficient current conversion can be obtained through the Spin Hall Effect in heavy metals such as Platinum or Tantalum. The conversion can also be obtained by exploiting the Edelstein Effect in Rashba interfaces and topological insulators.The spin to charge conversion by means of Inverse Edelstein Effect and inverse Spin Hall Effect can be studied by the spin pumping by ferromagnetic resonance technique. This manuscript present these two conversion mechanisms as well as the technique that was used to measure them, which is based on an electrical detection of the ferromagnetic resonance. Results on the spin to charge current conversion obtained in metals, oxide-based Rashba interfaces and topological insulators will be presented. Among these systems we have demonstrated the possibility to tune the conversion efficiency by using a gate voltage in a two-dimensional electron gas at the surface of an oxide SrTiO3. Moreover it is possible to tune this effect, a remanent way, thanks to the ferroelectricity obtained in SrTiO3 at cryogenic temperatures.Other studied systems such as topological insulators HgTe and Sb2Te3 also have promising properties for an efficient spin to charge current conversion at room temperature. In particular we showed than in HgTe by using a thin HgCdTe protective layer, it is possible to obtain a spin to charge current conversion efficiency one order of magnitude larger than in Pt.These results suggest that stwo dimensional electron gases at oxide interfaces and topological insulators have a strong potential for the efficient detection of spin currents for possible beyond CMOS applications.

> Discover all the winners of 2020 Thesis Awards


Updated on June 3, 2020

Relocation

The College and the doctoral schools (except Philo) moved on September 1st, 2020 to join the Maison Jean Kuntzmann at 110 rue de la Chimie 38400 Saint-Martin-d'Hères on the University Campus (Tram B and C, stops "Bibliothèques universitaires").
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