Magnetic anisotropy of quaternary GaMnAsP ferromagnetic semiconductor

Abstract

We report a systemeatic investigation of magnetic anisotropy of quaternary GaMnAsP ferromagnetic semiconductor films by magneto-transport. Hall measurements showed a transition of the easy magnetization direction from in-plane to out-of plane with incorporation of the P into the GaMnAs films. Quantitative information on magnetic anisotropy of the films is obtained by fitting the angular dependence of Hall resistance data to magnetic free energy using the coherent rotation model. Values of magnetic anisotropy parameters show that in-plane anisotropy decreases and out-of-plane anisotropy increases with increasing P content in these films. The out-of-plane magnetic anisotropy in GaMnAsP layers is further enhanced by low temperature annealing. By optimizing the growth and annealing conditions, we were able to obtain a Curie temperature of 125 K in such quaternary films, with strong out-of-plane anisotropy. This study showed that the magnetic anisotropy of the GaMnAsP films can be controlled by adjusting the concentration of the P, and by appropriate post-growth annealing.

Colossal negative magnetoresistance from hopping in insulating ferromagnetic semiconductors

“…1(a) shows versus magnetic field up to 12 T. It is noted that in the "hopping" regime ( Ω•cm), which corresponds to properties of insulating ferromagnetic semiconductors [18,22] , the dependence of on can be described experimentally by the universal relation . The curve thus reproduces the behavior of the magnetization, demonstrating that the anomalous Hall effect is dominated by hopping contribution [18,22] . This is expected, given that the resistivity of these two samples reaches the high values of 40 Ω•cm for sample S1 and more than 5000 Ω•cm for S2 at T < 1.5 K. Figs.…”

“…To resolve the issue that no single conduction law satisfies the entire conductivity curve at any magnetic field, we can express Eq. ( 2) as [18,34] :…”

“…Such localization increases with increasing concentration of phosphorus y. As we vary the properties of Ga 1-x Mn x As 1-y P y from metallic to this semi-insulating regime by increasing the value of y, our studies of the anomalous Hall effect (AHE) in this material show a clear transition from AHE described by Berry curvature to one that is determined by hopping [18] .…”

Ferromagnetic resonance and spin-wave resonances in GaMnAsP films

“…9 Using this series, we carried out a detailed quantitative investigation of magnetic anisotropy of Ga 1-x Mn x As 1-y P y films by ferromagnetic resonance (FMR) measurements, which allowed us to quantify both in-plane and out-of-plane anisotropy constants, thus providing a useful guide for understanding the magnetic behavior of this quaternary system as function of P concentration. The Ga 1-x Mn x As 1-y P y films were grown with a constant Mn content x ≈ 0.06, and with P content varied from y ≈ 0 to 0.15.…”