4:45 PM - QN06.02.09
Semiconductor/Ferromagnetic Insulator InAs/EuS Epitaxy
Yu Liu1,Peter Krogstrup1
University of Copenhagen1
Material development holds promise as the basis of topological quantum computing with Majorana fermions. These quasiparticles have been predicted at ends of semiconductor nanowires coupled to conventional superconductors [1-2]. These predictions were followed by a series of experiments providing transport signatures consistent with these theories [3-4]. These early measurements suffered from soft induced superconducting gap, which later was significantly improved by growing epitaxial semiconductor-superconductor (SE-SU) nanowires [5-6]. In order to reach the topological phase, an external magnetic field is needed to lift the spin degeneracy in these SE-SU systems, which brings an even larger challenge for achieving scalable solutions. Therefore, in order to integrate and scale up a topological quantum plane, materials that are intrinsically topological (without the need for an external applied field) would be highly preferable. Composite tri-crystals using ferromagnetic insulators (FMIs) in close proximity to the SE-SU structure have been proposed as a solution to lift the spin degeneracy , where the Zeeman splitting could be induced by the exchange field from the FMI.
In this work, we study hybrid SE-FMI epitaxy of EuS on different InAs crystallographic platforms as the initial basis of tri-crystal SE-SU-FMI NW systems. These SE-FMI systems prove to fullfil key requirements for the realization of topological quantum computing material without need of large external magnetic field:
1. The EuS thin film grown on (100) Zinc Blende InAs surface is fully conherent.
2. An exchange field exists by inducing magnetic moments into InAs of about 2 nm.
3. InAs/EuS NWs have strong shape-defined single magnetic domains along the NW length with Curie temperature of 19 K.
The results not only show the InAs/EuS hybrid crystals as promising candidates for topological quantum computing, but also confirm EuS as a promising FMI for various spin applications.
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