title: Berry phase mechanism of the anomalous Hall effect in a disordered two-dimensional magnetic semiconductor structure.
abstract: The anomalous Hall effect (AHE) arises from the interplay of spin-orbit interactions and ferromagnetic order and is a potentially useful probe of electron spin polarization, especially in nanoscale systems where direct measurement is not feasible. While AHE is rather well-understood in metallic ferromagnets, much less is known about the relevance of different physical mechanisms governing AHE in insulators. As ferromagnetic insulators, but not metals, lend themselves to gate-control of electron spin polarization, understanding AHE in the insulating state is valuable from the point of view of spintronic applications. Among the mechanisms proposed in the literature for AHE in insulators, the one related to a geometric (Berry) phase effect has been elusive in past studies. The recent discovery of quantized AHE in magnetically doped topological insulators - essentially a Berry phase effect - provides strong additional motivation to undertake more careful search for geometric phase effects in AHE in the magnetic semiconductors. Here we report our experiments on the temperature and magnetic field dependences of AHE in insulating, strongly-disordered two-dimensional Mn delta-doped semiconductor heterostructures in the hopping regime. In particular, it is shown that at sufficiently low temperatures, the mechanism of AHE related to the Berry phase is favoured.
authors.affiliation: National Research Center Kurchatov Institute, Moscow 123182, Russia.|P.N. Lebedev Physical Institute, Russian Acad. Sci., Moscow 119991, Russia.
authors.forename: L N
authors.initials: LN
authors.lastname: Oveshnikov
authors.affiliation: National Research Center Kurchatov Institute, Moscow 123182, Russia.|Low Temperature Physics Department, M.V. Lomonosov Moscow State University, Moscow 119991, Russia.
authors.forename: V A
authors.initials: VA
authors.lastname: Kulbachinskii
authors.affiliation: P.N. Lebedev Physical Institute, Russian Acad. Sci., Moscow 119991, Russia.
authors.forename: A B
authors.initials: AB
authors.lastname: Davydov
authors.affiliation: National Research Center Kurchatov Institute, Moscow 123182, Russia.|P.N. Lebedev Physical Institute, Russian Acad. Sci., Moscow 119991, Russia.
authors.forename: B A
authors.initials: BA
authors.lastname: Aronzon
authors.affiliation: Ioffe Institute, Russian Acad. Sci., St. Petersburg 194021, Russia.|Peter the Great St. Petersburg Polytechnic University, St. Petersburg 195251, Russia.
authors.forename: I V
authors.initials: IV
authors.lastname: Rozhansky
authors.affiliation: Ioffe Institute, Russian Acad. Sci., St. Petersburg 194021, Russia.
authors.forename: N S
authors.initials: NS
authors.lastname: Averkiev
authors.affiliation: Institute for Theoretical and Applied Electrodynamics, Russian Acad. Sci., Moscow 125412, Russia.
authors.forename: K I
authors.initials: KI
authors.lastname: Kugel
authors.affiliation: Materials Science Division, Argonne National Laboratory, Lemont, IL 60439, USA.|Department of Theoretical Physics, Tata Institute of Fundamental Research, Mumbai 400005, India.
authors.forename: V
authors.initials: V
authors.lastname: Tripathi