Universal description of surface magnetism via magnetoelectric effects

Datum

16.01.2025

Zeit

13:00 - 15:00

Sprecher

Andrea Urru

Zugehörigkeit

Rutgers University

Serie

TUD nanoSeminar

Sprache

en

Hauptthema

Physik

Andere Themen

Physik

Host

Arezoo Dianat

Beschreibung

Due to their reduced symmetry, surfaces often host physical phenomena that are absent in the corresponding bulk material. Of particular interest for spintronics applications is the case of surfaces showing a non-vanishing magnetic dipole per unit area, named “surface magnetization” [1-2], which can occur despite the corresponding bulk being a perfectly compensated antiferromagnet with zero net magnetization. Such surface magnetization underlies intriguing physical phenomena like interfacial magnetic coupling, and can be used as a readout method of antiferromagnetic domains [3-4]. In this talk, I will first introduce a classification scheme based on whether the surface of interest is magnetically compensated or uncompensated if the bulk magnetic order is retained at the surface. Then, I will show how surface magnetization can be understood in terms of bulk magnetoelectric effects, whereby an applied electric field induces a net magnetization. The link between a bulk magnetoelectric response and surface magnetization is intuitively expected by the fact that the abrupt termination of a bulk to create a surface generates also an effective electric field at the surface. This bulk-to-boundary correspondence serves as the ground for a universal description of surface magnetization in antiferromagnets, which has been lacking thus far [5]. Finally, I will use density functional calculations to illustrate that nominally compensated surfaces in Cr2 O3 and centrosymmetric FeF 2 develop a finite magnetization at the surface, in agreement with our predictions based on the corresponding bulk magnetoelectric response.
 [1] K. D. Belashchenko, Phys. Rev. Lett. 105, 147204 (2010)
 [2] M. S. Wornle et al., Phys. Rev. B 103, 094426 (2021)
 [3] N. Hedrich et al., Nat. Phys. 17, 574 (2021)
 [4] J. Nogues and I. K. Schuller, J. Magn. Magn. Mater. 192, 203 (1999).
 [5] S. F. Weber, A. Urru, S. Bhowal, C. Ederer, and N. A. Spaldin, Phys. Rev. X 14, 021033 (2024).

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Letztmalig verändert: 17.01.2025, 07:38:54