title: Observation of anomalous Hall effect in a non-magnetic two-dimensional electron system.
abstract: Anomalous Hall effect, a manifestation of Hall effect occurring in systems without time-reversal symmetry, has been mostly observed in ferromagnetically ordered materials. However, its realization in high-mobility two-dimensional electron system remains elusive, as the incorporation of magnetic moments deteriorates the device performance compared to non-doped structure. Here we observe systematic emergence of anomalous Hall effect in various MgZnO/ZnO heterostructures that exhibit quantum Hall effect. At low temperatures, our nominally non-magnetic heterostructures display an anomalous Hall effect response similar to that of a clean ferromagnetic metal, while keeping a large anomalous Hall effect angle θAHE≈20°. Such a behaviour is consistent with Giovannini-Kondo model in which the anomalous Hall effect arises from the skew scattering of electrons by localized paramagnetic centres. Our study unveils a new aspect of many-body interactions in two-dimensional electron systems and shows how the anomalous Hall effect can emerge in a non-magnetic system.
authors.affiliation: RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan.
authors.forename: D
authors.initials: D
authors.lastname: Maryenko
authors.affiliation: RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan.
authors.forename: A S
authors.initials: AS
authors.lastname: Mishchenko
authors.affiliation: RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan.|Department of Applied Physics and Quantum Phase Electronics Center (QPEC), University of Tokyo, Tokyo 113-8656, Japan.
authors.forename: M S
authors.initials: MS
authors.lastname: Bahramy
authors.affiliation: Max-Planck-Institut fr Mikrostrukturphysik, Weinberg 2, 06120 Halle, Germany.|Institut für Theoretische Physik, Johannes Kepler Universität, A 4040 Linz, Austria.
authors.forename: A
authors.initials: A
authors.lastname: Ernst
authors.affiliation: Department of Applied Physics and Quantum Phase Electronics Center (QPEC), University of Tokyo, Tokyo 113-8656, Japan.
authors.forename: J
authors.initials: J
authors.lastname: Falson
authors.affiliation: Department of Applied Physics and Quantum Phase Electronics Center (QPEC), University of Tokyo, Tokyo 113-8656, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Kozuka
authors.affiliation: Institute for Materials Research, Tohoku University, Sendai 908-8577, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Tsukazaki
authors.affiliation: RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan.|Department of Applied Physics and Quantum Phase Electronics Center (QPEC), University of Tokyo, Tokyo 113-8656, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Nagaosa
authors.affiliation: RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan.|Department of Applied Physics and Quantum Phase Electronics Center (QPEC), University of Tokyo, Tokyo 113-8656, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Kawasaki