Nanometer-scale magnetic MnAs particles in GaAs grown by molecular beam epitaxy

Abstract

Spherical MnAs ferromagnetic particles with controllable diameters (5–30 nm) are embedded in a high quality GaAs matrix. The particles are formed in a two step process consisting of the epitaxy of a homogeneous Ga1−xMnxAs layer at low temperatures using molecular beam epitaxy followed by phase separation upon annealing. During the annealing step, the excess arsenic in the as-grown film forms magnetic MnAs precipitates with the Mn from the Ga1−xMnxAs lattice. Structural and room-temperature magnetic properties of the heterogeneous GaAs:MnAs films are described. The magnetic MnAs rich layers can be incorporated into semiconductor heterostructures as demonstrated by growing (GaAs/AlAs) multiple quantum well structures in combination with GaAs:MnAs layers.

Spintronics: Fundamentals and applications

“…Early work on (Ga,Mn)As (De Boeck et al, 1996) showed the low solubility of Mn and the formation of magnetic nanoclusters characteristic of many subsequent compounds and different magnetic impurities. The presence of such nanoclusters often complicates accurate determination of T C as well as of whether the compound is actually in a single phase.…”

Neutron scattering studies of nanomagnetism and artificially structured materials

“…These precipitates are of considerable interest in their own right: they remain ferromagnetic above room temperature, and their dimensions are typically about 30 nm in diameter [264]. An example of such a nanocrystallite precipitated in a (Ga, Mn)As matrix, imaged by TEM, is shown in Figure 22.…”

(Ga, Gd, As) film growth on GaAs substrate by low-energy ion-beam deposit

“…Gallium arsenide (GaAs) has several properties, so it is superior to silicon for use in optoelectronic devices. Increasing attention has been paid to the preparation of diluted magnetic semiconductors (DMS), in recent years after the III-V-based DMS, such as (In, Mn)As and (Ga, Mn)As, has been successfully fabricated by low-temperature MBE [2][3][4][5]. The ferromagnetic transition temperature (T c ) has increased a little by optimal annealing study [6] in comparison with the highest reported T c ¼ 110 K.…”