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Theme 3 colloquium: "Berry phase engineering at oxide interfaces" (Lecture)

Tuesday 20 November 2018Add to my calendar
from 16:00
HG 00.303
prof. Andrea Caviglia (TUD)

prof. Andrea CaviggiaGeometric phases in condensed matter play a central role in many intriguing phenomena such as the quantum, spin and anomalous Hall effect. In contrast to the quantum Hall effect, which is characterized by a global topological invariant and robust against perturbations, the anomalous Hall effect depends on the Berry curvature of occupied bands at the Fermi level and is therefore highly sensitive to subtle changes in the band structure. A unique platform for its manipulation is provided by transition metal oxides, owing to the delicate balance between energy scales and the possibility of creating atomically sharp interfaces, where nanometer-scale electronic and magnetic reconstructions can occur. We demonstrate how electronic transport in the ultrathin ferromagnetic oxide SrRuO3 can be manipulated by imposing asymmetric boundary conditions in the form of two dissimilar interfaces. Measurements of the AHE, which probe the Berry curvature of occupied bands, reveal the presence of two spatially-separated, spin-polarized conduction channels. Using theoretical calculations we show that the Berry curvature of the spin-polarized Ru bands is modified near the SrTiO3 and SrIrO3 interfaces, resulting in opposite signs of the anomalous Hall conductivity. Our study demonstrates how reconstructions at oxide interfaces can be used to control spin and charge accumulation on a nanometer-scale, opening new routes towards spintronics and topological electronics.

prof. Alexey Kimel