In a prototypical ferromagnet (Ga,Mn)As based on a III–V semiconductor, substitution of divalent Mn atoms into trivalent Ga sites leads to severely limited chemical solubility and metastable specimens available only as thin films. The doping of hole carriers via (Ga,Mn) substitution also prohibits electron doping. To overcome these difficulties, Masek et al. theoretically proposed systems based on a I–II–V semiconductor LiZnAs, where isovalent (Zn,Mn) substitution is decoupled from carrier doping with excess/deficient Li concentrations. Here we show successful synthesis of Li_1+y(Zn_1−xMn_x)As in bulk materials. Ferromagnetism with a critical temperature of up to 50 K is observed in nominally Li-excess (y=0.05–0.2) compounds with Mn concentrations of x=0.02–0.15, which have p-type metallic carriers. This is presumably due to excess Li in substitutional Zn sites. Semiconducting LiZnAs, ferromagnetic Li(Zn,Mn)As, antiferromagnetic LiMnAs, and superconducting LiFeAs systems share square lattice As layers, which may enable development of novel junction devices in the future.

The observation of a high-mobility two-dimensional electron gas between two insulating complex oxides, especially LaAlO₃/SrTiO₃, has enhanced the potential of oxides for electronics. The occurrence of this conductivity is believed to be driven by polarization discontinuity, leading to an electronic reconstruction. In this scenario, the crystal orientation has an important role and no conductivity would be expected, for example, for the interface between LaAlO₃ and (110)-oriented SrTiO₃, which should not have a polarization discontinuity. Here we report the observation of unexpected conductivity at the LaAlO₃/SrTiO₃ interface prepared on (110)-oriented SrTiO₃, with a LaAlO₃-layer thickness-dependent metal-insulator transition. Density functional theory calculation reveals that electronic reconstruction, and thus conductivity, is still possible at this (110) interface by considering the energetically favourable (110) interface structure, that is, buckled TiO₂/LaO, in which the polarization discontinuity is still present. The conductivity was further found to be strongly anisotropic along the different crystallographic directions with potential for anisotropic superconductivity and magnetism, leading to possible new physics and applications.

To obtain room-temperature ferromagnetic semiconductors and to realize the room-temperature quantum anomalous Hall effect (QAHE) have been big challenges for a long time. Here we report that, on the basis of first-principles calculations, ${\mathrm{Pd}\mathrm{Br}}_3$, ${\mathrm{Pt}\mathrm{Br}}_3$, ${\mathrm{Pd}\mathrm{I}}_3$, and ${\mathrm{Pt}\mathrm{I}}_3$ monolayers are ferromagnetic semiconductors that could exhibit a high-temperature QAHE. The Curie temperatures estimated by Monte Carlo simulations are 350 and 375 K for ${\mathrm{Pd}\mathrm{Br}}_3$ and ${\mathrm{Pt}\mathrm{Br}}_3$ monolayers, respectively. The band gaps of ${\mathrm{Pd}\mathrm{Br}}_3$ and ${\mathrm{Pt}\mathrm{Br}}_3$ are found to be 58.7 and 28.1 meV, respectively, with the generalized-gradient approximation and 100.8 and 45 meV, respectively, with the HSE06 method, being quite well in favor of observing the room-temperature QAHE. It is shown that the large band gaps are induced from multiorbital electron correlations. By carefully studying the stabilities of the four aforementioned monolayers, we unveil that they could be feasible for use in experiments. The present work sheds light on the development of spintronic devices by use of room-temperature ferromagnetic semiconductors and the implementation of dissipationless devices by application of the room-temperature QAHE.

By density-functional-theory calculations, we predict a stable two-dimensional (2D) ferromagnetic semiconductor, ${\mathrm{Cr}}_2{\mathrm{Ge}}_2{\mathrm{Se}}_6$, where the Curie temperature $T_C$ can be dramatically increased beyond room temperature by applying a few-percent strain. In addition, the anomalous Hall conductivity in 2D ${\mathrm{Cr}}_2{\mathrm{Ge}}_2{\mathrm{Se}}_6$ and ${\mathrm{Cr}}_2{\mathrm{Ge}}_2{\mathrm{Te}}_6$ is predicted to be comparable to that in the ferromagnetic metals $\mathrm{Fe}$ and $\mathrm{Ni}$, and is an order of magnitude larger than that in the diluted magnetic semiconductor $\mathrm{Ga}$($\mathrm{Mn}$,$\mathrm{As}$). Based on superexchange interactions, the increased $T_C$ in 2D ${\mathrm{Cr}}_2{\mathrm{Ge}}_2{\mathrm{Se}}_6$ caused by strain can be understood by the decreased energy difference between $3d$ orbitals of $\mathrm{Cr}$ and $4p$ orbitals of $\mathrm{Se}$. Our findings highlight the microscopic mechanism to obtain room-temperature ferromagnetic semiconductors by strain.

We report the discovery of a diluted magnetic semiconductor, Li(Zn,Mn)P, in which charge and spin are introduced independently via lithium off-stoichiometry and the isovalent substitution of Mn${}^{2+}$ for Zn${}^{2+}$, respectively. Isostructural to (Ga,Mn)As, Li(Zn,Mn)P was found to be a $p$-type ferromagnetic semiconductor with excess lithium providing charge doping. First-principles calculations indicate that excess Li is favored to partially occupy the Zn site, leading to hole doping. Ferromagnetism with Curie temperature up to 34 K is achieved while the system still shows semiconducting transport behavior.

We show, both experimentally and theoretically, a novel route to obtain giant room temperature spin-Hall effect due to surface-assisted skew scattering. In the experiment, we report the spin-Hall effect in Pt-doped Au films with different thicknesses $t_N$. The giant spin-Hall angle ${\gamma }_S=0.12\pm 0.04$ is obtained for $t_N=10\mathrm{nm}$ at room temperature, while it is much smaller for the $t_N=20\mathrm{nm}$ sample. Combined ab initio and quantum Monte Carlo calculations for the skew scattering due to a Pt impurity show ${\gamma }_S\cong 0.1$ on the Au (111) surface, while it is small in bulk Au. The quantum Monte Carlo results show that the spin-orbit interaction of the Pt impurity on the Au (111) surface is enhanced, because the Pt $5d$ levels are lifted to the Fermi level due to the valence fluctuation. In addition, there are two spin-orbit interaction channels on the Au (111) surface, while only one in bulk Au.