Thursday May 15 at 2:00 pm (Paris time), Room Boreau, building C, 2nd floor, at LPEM in hybrid format: The anomalous Hall effect in α-MnTe thin films
By Badih A. Assaf, Physics and Astronomy, University of Notre Dame.
The anomalous Hall effect (AHE) is a Hall effect that arises at zero magnetic field in ferromagnets that have a spontaneous magnetization. In the simplest picture, its magnitude is proportional to the out-of-plane component of magnetization. Antiferromagnets are magnetically ordered materials with no net magnetization, so by that logic they are not expected to exhibit an AHE. For that same reason, antiferromagnets were considered useless for magnetic memory devices where information is stored by varying the orientation of the magnetization and detected by measuring the electron spin polarization. The recent understanding of how magnetocrystalline symmetry impacts the origin of the AHE challenges this simple picture. It raises hopes for the implementation of a special class of low symmetry antiferromagnets, called altermagnets, as functional magnetic materials that can intrinsically host spin polarization. In this talk, I will present our findings on the anomalous Hall effect measured in α-MnTe – an altermagnet [1]. In α-MnTe thin films grown molecular beam epitaxy, we systematically measure a strong spontaneous AHE despite the material having a nearly vanishing spontaneous magnetization [2]. I will discuss the origin of this effect, in the context of a detailed characterization study that we carried, to reveal the structural properties of this material [3].
[1] Smejkal et al., Phys. Rev. X 12 031042 (2022).
[2] S. Bey et al. arxiv2409.04567.
[3] S. Bey et al. arxiv2504.12126.
ID: 857 2923 1484
Passcode: F.H.Hund