Bulletin of the American Physical Society
APS March Meeting 2014
Volume 59, Number 1
Monday–Friday, March 3–7, 2014; Denver, Colorado
Session J39: Invited Session: Transport, Superconductivity, and Magnetism at the LAO/STO Interface
2:30 PM–4:54 PM,
Tuesday, March 4, 2014
Room: Mile High Ballroom 2A-3A
Sponsoring Unit: DCMP
Chair: Allan H. MacDonald, University of Texas at Austin
Abstract ID: BAPS.2014.MAR.J39.3
Abstract: J39.00003 : Chiral magnetism at oxide interfaces*
3:42 PM–4:18 PM
Preview Abstract Abstract
(Ohio State University)
There are tantalizing hints of magnetism at the n-type LaAlO$_3$/SrTiO$_3$ interface, but the experimental evidence remains controversial in view of some of the differences between different samples and probes. I will argue that if magnetism exists at interfaces, symmetry arguments imply chiral interactions  that lead to a spiral ground state in zero external field and skyrmion crystals for $H \neq 0$. I will next present a microscopic model that provides a possible mechanism for the formation of local moments. I will show that the coupling of these moments to itinerant electrons leads to ferromagnetic double exchange together with Dzyaloshinskii-Moriya (DM) interactions and an easy-plane ``compass'' anisotropy, which arise from Rashba spin-orbit coupling (SOC) due to the lack of inversion symmetry at the interface. The compass term, often ignored in the literature on chiral magnetism, is shown to play a crucial role in determining the magnetic ground state. I will compare our results with existing torque magnetometry data on LAO/STO and try to reconcile it with scanning SQUID magnetometry. Finally, I will present the phase diagram in a field and show that easy-plane anisotropy stabilizes an unexpectedly large skyrmion crystal phase and describe its properties. (Work done in collaboration with Sumilan Banerjee, Onur Erten, Daniel Kestner and James Rowland). \\[4pt]  S. Banerjee, O. Erten and M. Randeria, Nature Physics 9, 626 (2013).
*Supported by DOE-BES DE-SC0005035, NSF-DMR-1006532 and NSF MRSEC DMR-0820414.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2014.MAR.J39.3
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