Magnetic properties ofCo∕GaAs(110)

Abstract

We observed three magnetic states of an ultrathin, atomically well-ordered Co film grown on a cleaved GaAs͑110͒ substrate. For a Co thickness less than 3.4 monolayers ͑ML͒, we find a ferromagnetically dead layer associated with the formation of interfacial Co 2 GaAs. For thicknesses greater than 4.1 ML, the Co film grows with a bcc structure that contains 6 at. % Ga. The films are ferromagnetic with an easy axis along the ͓110͔ direction. This magnetic state persists up to a thickness of 7 ML, at which point an abrupt in-plane spin-reorientation transition reorients the magnetization along the ͓001͔ direction.

Reconstructed bcc Co films on the surface

“…Co films up to 35 nm were grown on GaAsð1 1 0Þ [1] with a magnetization slightly lower than the bulk value. A recent study showed that Co forms an interfacial alloy at the GaAsð1 1 0Þ surface followed by bcc Co containing 6 at.% Ga [23]. Using Sb as a surfactant partly leads to a removal of lattice distortions and to an improvement of the magnetic properties [24].…”

Chemical and morphological characterizations of CoNi alloy nanoparticles formed by co-evaporation onto highly oriented pyrolytic graphite

“…Although such studies have been carried out for several decades, on substrates as varied as Si, Ga, As, Pt, Pd and highly oriented pyrolytic graphite (HOPG) [4][5][6][7][8][9], most of these studies were confined to pure metal NPs. Recently, bimetallic NPs have become an interesting research field due to certain properties of nanoscale alloys, which may exist in a number of structures and phases that are different from those of the corresponding bulk metals [10,11].…”

Magnetic anisotropy in epitaxial Mn5Ge3films

“…[21][22][23] For example, in the Co/Ge(111) heterostructure, the critical thickness leading to the paramagnetic-ferromagnetic transition lies between 5 and 8Å. 24 Such a magnetic dead layer could result from various phenomena: interdiffusion and formation of an interfacial alloy that is generally not ferromagnetic, 21,22,25 interfacial roughness, 23 proximity of a nonmagnetic material, 26 and strain at the interface. 27 Here, the structural and magnetic analyses do not allow us to determine precisely the origin of the FDL.…”