Uniaxial magnetic anisotropy of submicron MnAs ferromagnets in GaAs semiconductors

Abstract

Submicron (100–500 nm) room-temperature ferromagnets of MnAs have been successfully incorporated into GaAs semiconductor substrates by Mn+ ion implantation and subsequent heat treatment at 920 °C for 1 s in a nitrogen gas. Atomic force microscopy indicates an epitaxial relation of [0001] oriented hexagonal MnAs crystallites on (001) GaAs substrates: [11 2̄0]MnAs∥[110]GaAs. A stronger shape anisotropy along [110]GaAs is observed for the smaller crystallites. Magnetic characterizations by superconducting quantum interference device reveal uniaxial in-plane magnetic anisotropy of the sample. Magnetic force microscopy imaging shows that the uniaxial magnetic anisotropy comes from the alignment of magnetic dipoles along the magnetic easy [11 2̄0] axis of MnAs, which is parallel to [110]GaAs.

High Curie temperature and perpendicular magnetic anisotropy in homoepitaxial InMnAs films

“…For bulk MnAs or nanocrystalline MnAs in GaAs, the Curie temperature is above 300 K [33,34]. As shown in Figure 1(b) and Figure 3, there is no indication of secondary magnetic phase with a higher T C .…”

“…The most probable secondary phase is MnAs, like in the case of Mn implanted GaAs upon rapid thermal annealing [33,34]. For bulk MnAs or nanocrystalline MnAs in GaAs, the Curie temperature is above 300 K [33,34].…”

Diluted Magnetic III-V Semiconductors

“…For both InMnAs and GaMnAs it was shown that in general Mn substitutes cation sublattice (In or Ga) [28]. It is worthwhile to mention that annealing of LT GaMnAs leads to segregation: Mn concentrates in MnAs precipitates leaving apart nearly pure GaAs [29].…”

Electric Field Effect in Diluted Magnetic Insulator AnataseCo: TiO2

“…20,21 The O-MCD test has been demonstrated in different systems including some oxide-based materials. 16,17,22 The electric field modulation, which in some 4 sense is the most stringent test of intrinsic ferromagnetism, has, however, been demonstrated only in III-V DMS systems 18,19 , but not yet in any oxide-DMS materials. In this paper we report the first successful implementation of an external electric field modulation of ferromagnetism in DMS anatase Co:TiO 2 , grown under conditions suggested to yield uniform matrix incorporation of cobalt.…”

“…It is generally suggested that any new material must satisfy three specific tests to qualify as an intrinsic (carrier-induced, uniformly dispersed dopants) diluted ferromagnetic system: Observation of a) Anomalous Hall effect (AHE) 14,15 , b) optical magnetic circular dichroism (O-MCD) 16,17 , and c) electric field induced modulation of magnetization 18,19 . We have recently shown that observation of AHE, although desirable, is not really a strict test and can be realized even in a sample with non-percolating magnetic clusters.…”