We report a photoinduced change of the coercive field, i.e., a photocoercivity effect (PCE), under very low intensity illumination of a low-doped (Ga,Mn)As ferromagnetic semiconductor. We find a strong correlation between the PCE and the sample resistivity. Spatially resolved dynamics of the magnetization reversal rule out any role of thermal heating in the origin of this PCE, and we propose a mechanism based on the light-induced lowering of the domain wall pinning energy. The PCE is local and reversible, allowing writing and erasing of magnetic images using light.
Two-dimensional chromium oxide fluoride CrOF sheet was studied based on density functional theory. The investigation indicates that the CrOF sheet is an intrinsic ferromagnetic semiconductor. The calculated low cleavage energy implies that the ferromagnetic semiconductor can be exfoliated from its bulk form. The corresponding Curie temperature is 150 K. In particular, the Curie temperature increases up to 410 K under hole doping and the CrOF sheet becomes a half-metal. The versatile electronic and magnetic properties indicate that the two-dimensional CrOF sheet can be a promising candidate for…
We successfully dope the magnetically silent double perovskite semiconductor Sr2GaSbO6 to induce ferromagnetism and tune its band gap, with Ga3+ partially substituted by the magnetic trivalent cation Mn3+, in a rigid cation ordering with Sb5+. Our new ferromagnetic semiconducting Sr2Ga1-xMnxSbO6 double perovskite, which crystallizes in tetragonal symmetry (space group I4/m) and has tunable ferromagnetic ordering temperature and band gap, suggests that magnetic ion doping of double perovskites is a productive avenue towards obtaining materials for application in next-generation oxide-based spin…
We present high-temperature ferromagnetism and large magnetic anisotropy in heavily Fe-doped n-type ferromagnetic semiconductor (In1-x,Fex)Sb (x = 20 - 35%) thin films grown by low-temperature molecular beam epitaxy. The (In1-x,Fex)Sb thin films with x = 20 - 35% maintain the zinc-blende crystal and band structure with single-phase ferromagnetism. The Curie temperature (TC) of (In1-x,Fex)Sb reaches 390 K at x = 35%, which is significantly higher than room temperature and the highest value so far reported in III-V based ferromagnetic semiconductors. Moreover, large coercive force (HC = 160 Oe) …
We carefully investigated the ferromagnetic coupling in the as-grown and annealed ferromagnetic semiconductor GaMnAs/AlGaMnAs bilayer devices. We observed that the magnetic interaction between the two layers strongly affects the magnetoresistance of the GaMnAs layer with applying out of plane magnetic field. After low temperature annealing, the magnetic easy axis of the AlGaMnAs layer switches from out of plane into in-plane and the interlayer coupling efficiency is reduced from up to 0.6 to less than 0.4. However, the magnetic coupling penetration depth for the annealed device is twice that o…
Spin injection using ferromagnetic semiconductors at room temperature is a building block for the realization of spin-functional semiconductor devices. Nevertheless, this has been very challenging due to the lack of reliable room-temperature ferromagnetism in well-known group IV and III-V based semiconductors. Here, we demonstrate room-temperature spin injection by using spin pumping in a (Ga,Fe)Sb / BiSb heterostructure, where (Ga,Fe)Sb is a ferromagnetic semiconductor (FMS) with high Curie temperature (TC) and BiSb is a topological insulator (TI). Despite the very small magnetization of (Ga,…
Annealing-induced enhancement of ferromagnetism and nano-particle formation in ferromagnetic-semiconductor GeFe
我们报道了退火引起的IV族铁磁半导体GeFe铁磁性增强和纳米颗粒形成。当退火温度低于500°C时，我们成功地将Ge 0.895 Fe 0.105薄膜的居里温度提高到~220 K，同时保持单一的铁磁相。相反，当在600°C退火时，在膜中形成具有堆垛层错和孪晶的单晶GeFe纳米颗粒，其具有接近室温的高居里温度。我们的研究结果表明，退火是非常有效的，以提高磁性能的GeFe的高温操作的自旋注入器件的Si或Ge基。
A systematic study of hole compensation effect on magnetic properties, which is controlled by defect compensation through ion irradiation, in (Ga,Mn)As, (In,Mn)As and (Ga,Mn)P is presented in this work. In all materials, both Curie temperature and magnetization decrease upon increasing the hole compensation, confirming the description of hole mediated ferromagnetism according to the p-d Zener model. The material dependence of Curie temperature and magnetization versus hole compensation reveals that the manipulation of magnetic properties in III-Mn-V dilute ferromagnetic semiconductors by ion i…
To obtain room temperature ferromagnetic semiconductors is one of big challenges in science, and also premises essentially to realize room temperature quantum anomalous Hall effect (QAHE), both of which are quite expected for a long time. Here we report that, based on first-principles calculations, PdBr3, PtBr3, PdI3 and PtI3 monolayers are ferromagnetic semiconductors with possible high temperature QAHE. Monte Carlo simulations give Curie temperatures 350 K and 375 K for PdBr3 and PtBr3 monolayers, respectively. These two-dimensional (2D) materials are Chern insulators. The band gaps of PdBr3…
The seeking of room temperature ferromagnetic semiconductors, which take advantages of both the charge and spin degrees of freedom of electrons to realize a variety of functionalities in devices integrated with electronic, optical, and magnetic storage properties, has been a long-term goal of scientists and engineers. Here, by using the spin-polarized density functional theory calculations, we predict a new series of high temperature ferromagnetic semiconductors based on the melilite-type oxysulfide Sr$_2$MnGe$_2$S$_6$O through hole (K) and electron (La) doping. Due to the lack of strong antif…
Cr2Ge2Te6 is an intrinsic ferromagnetic semiconductor with van der Waals type layered structure, thus represents a promising material for novel electronic and spintronic devices. Here we combine scanning tunneling microscopy and first-principles calculations to investigate the electronic structure of Cr2Ge2Te6. Tunneling spectroscopy reveals a surprising large energy level shift and change of energy gap size across the ferromagnetic to paramagnetic phase transition, as well as a peculiar double-peak electronic state on the Cr-site defect. These features can be quantitatively explained by densi…
