Speaker

Lieu

Moyen amphi (LPS) + ONLINE (Zoom)
Moyen amphi (LPS) + ONLINE (Zoom)

Date

12 Mai 2022
Expired!

Heure

11h00 - 12h00

A.MANCHON: Unconventional transport in noncollinear antiferromagnets

The rather old interest in antiferromagnets has been entirely renewed in the past decade with the discovery of novel means to control the antiferromagnetic order using electrical current and the observation of topological transport properties[1,2]. I will review the theoretical and experimental progress made over the past few years on noncollinear antiferromagnets (Fig. 1). In contrast with their collinear counterparts, these materials can display anomalous Hall effect[3] as well as spin polarization, which widens the horizon of spintronics research. I will focus on recent theoretical developments that reveal the exotic transport properties of these materials.
 
I will first briefly present the state of the art of antiferromagnetic spintronics, with key mechanisms such spin Hall effect and spin transfer torque. I will particularly discuss how collinear antiferromagnets can be manipulated using spin currents[4]. Then, I will move to noncollinear antiferromagnets, and show how conduction electrons experience an effective spin-orbit coupling that can lead to unconventional mechanisms such as anomalous Hall effect[5], magnetic spin Hall effect[2] as well as spin polarization. I will then demonstrate that upon inversion symmetry breaking, the spin texture in momentum space becomes antisymmetric, enabling the creation of nonequilibrium spin torques even in the absence of spin-orbit coupling. Finally, I will discuss the conditions under which noncollinear antiferromagnets can convey spin information through either diffusive or superfluid spin currents [6].

[1] Baltz, Manchon et al. Review of Modern Physics 90, 015005(2018).
[2] Bonbien et al., Journal of Physics D: Applied Physics 55, 103002(2022).
[3] Chen et al., PRL 112, 017205(2014); Nakatsuji et al., Nature 527, 212 (2015).
[4] Zelezny et al., PRL 113, 157201(2014); Manchon, J. Phys. Condens. Matter 29, 104002(2017).
[5] Ndiaye et al., Physical Review B 100, 144440 (2019).
[6] Goli and Manchon, Physical Review B 103, 104425 (2021).
Fig.1: Example of noncollinear antiferromagnet displaying quantum anomalous Hall effect