In-plane to perpendicular magnetic anisotropy switching in heavily-Fe-doped ferromagnetic semiconductor (Ga,Fe)Sb with high Curie temperature

Abstract

We report switching of magnetic anisotropy (MA) from in-plane to perpendicular with increasing the thickness d of a (001)-oriented ferromagnetic-semiconductor (FMS) (Ga0.7,Fe0.3)Sb layer with a high Curie temperature (TC > 320 K), using ferromagnetic resonance at room temperature. We show that the total MA energy (E⊥) along the [001] direction changes its sign from positive (inplane) to negative (perpendicular) with increasing d above an effective critical value d C * ~ 42 nm.We reveal that (Ga,Fe)Sb has two-fold symmetry in the film plane. Meanwhile, in the plane perpendicular to the film including the in-plane [110] axis, the two-fold symmetry with the easy magnetization axis along [110] changes to four-fold symmetry with easy magnetization axis along <001> with increasing d. This peculiar behavior is different from that of (Ga,Mn)As, in which only the in-plane MA depends on the film thickness and has four-fold symmetry due to its dominant cubic anisotropy along the <100> axes. This work provides an important guide for controlling the easy magnetization axis of high-TC FMS (Ga,Fe)Sb for room-temperature device applications.*

High-temperature intrinsic ferromagnetism in heavily Fe-doped GaAs layers

“…Thus, the obtained (Ga,Fe)As layer of the structure 200-25 is a vertical periodic system consisting of the nano-columnar regions of (Ga,Fe)As with higher Fe concentration separated by the regions of (Ga,Fe)As DMS with less Fe concentration. The similar structure with the nanocolumnar Fe-enriched DMS region was observed in the 40-nm-thick (Ga 0.7 ,Fe 0.3 )Sb layer obtained by MBE on the AlSb buffer layer [4].…”

Evolution of Fe 3d impurity band state as the origin of high Curie temperature in the p -type ferromagnetic semiconductor (Ga,Fe)Sb

“…Additionally, as for the deterioration of the crystal quality, a theoretical study of computational many-body methods for manganite La1-xSrxMnO3 suggests that the pseudogap features appear at EF when the system contains ferromagnetic cluster regions in an insulating background 42 . Since the Fe distribution in heavily-Fe-doped (Ga,Fe)Sb is reportedly nonuniform 43 , the inhomogeneity will lead to the pseudogap formation at EF. Then, the observed pseudogap behavior likely reflects the effect of U on the 𝑒 ↓ state and/or the nonuniform distribution of the Fe ions.…”

Spin-valve magnetoresistance in ferromagnetic semiconductor (Ga, Fe)Sb heterostructures with high Curie temperature

“…34 The linear background MR of sample A is removed so that the MR ratio is constant at high magnetic field (> 7 kOe). The negative background MR in sample C and D is fitted using the modified Khosla-Fischer model 32 Fig. S3.…”

“…The (Ga,Fe)Sb layers are designed to have a high TC (= 260 K) and a perpendicular magnetic anisotropy at low temperature. 29,30,32 We vary the thickness tInAs of InAs to be 0, 3, 6, 9 nm (denoted as sample A, B, C, D, respectively). Sample A, which does not contain an InAs layer, serves as a reference.…”