Colossal Magnetoresistive Switching Induced by d Ferromagnetism of MgO in a Semiconductor Nanochannel Device with Ferromagnetic Fe/MgO Electrodes.

Exploring potential spintronic functionalities in resistive switching (RS) devices is of great interest for creating new applications, such as multifunctional resistive random-access memory and novel neuromorphic computing devices. In particular, the importance of the spin-triplet state of cation vacancies in oxide materials, which is induced by localized and strong O-2p on-site Coulomb interactions, in RS devices has been overlooked. d ferromagnetism sometimes appears due to the spin-triplet state and ferromagnetic Zener's double exchange interactions between cation vacancies, which are occasionally strong enough to make nonmagnetic oxides ferromagnetic.

Exceptionally high saturation magnetisation in Eu-doped magnetite stabilised by spin-orbit interaction.

The significance of the spin-orbit interaction is very well known in compounds containing heavier elements such as the rare-earth Eu ion. Here, through density functional calculations, we investigated the effect of the spin-orbit interaction on the magnetic ground state of Eu doped magnetite (FeO:Eu). By examining all possible spin alignments between Eu and magnetite's Fe, we demonstrate that Eu, which is most stable when doped at the tetrahedral site, adapts a spin almost opposite the substituted Fe.

Ferromagnetism and giant magnetoresistance in zinc-blende FeAs monolayers embedded in semiconductor structures.

Material structures containing tetrahedral FeAs bonds, depending on their density and geometrical distribution, can host several competing quantum ground states ranging from superconductivity to ferromagnetism. Here we examine structures of quasi two-dimensional (2D) layers of tetrahedral Fe-As bonds embedded with a regular interval in a semiconductor InAs matrix, which resembles the crystal structure of Fe-based superconductors. Contrary to the case of Fe-based pnictides, these FeAs/InAs superlattices (SLs) exhibit ferromagnetism, whose Curie temperature (T) increases rapidly with decreasing the InAs interval thickness t (T ∝ t), and an extremely large magnetoresistance up to 500% that is tunable by a gate voltage.

Hole-mediated ferromagnetism in a high-magnetic moment material, Gd-doped GaN.

As an exotic material in spintronics, Gd-doped GaN is known as a room temperature ferromagnetic material that possesses a large magnetic moment (4000per Gd ion). This paper theoretically proposes that the large magnetic moment and room temperature ferromagnetism observed in Gd-doped GaN is caused by N 2p holes based on the assumption that Ga-vacancies result from the introduction of Gd ions. This causes that the too large magnetic moment is estimated for Gd ions if only Gd ions contributed the magnetic moment.

Superconducting H5S2 phase in sulfur-hydrogen system under high-pressure.

Recently, hydrogen sulfide was experimentally found to show the high superconducting critical temperature (Tc) under high-pressure. The superconducting Tc shows 30-70 K in pressure range of 100-170 GPa (low-Tc phase) and increases to 203 K, which sets a record for the highest Tc in all materials, for the samples annealed by heating it to room temperature at pressures above 150 GPa (high-Tc phase). Here we present a solid H5S2 phase predicted as the low-Tc phase by the application of the genetic algorithm technique for crystal structure searching and first-principles calculations to sulfur-hydrogen system under high-pressure.

Computational materials design of defect-induced ferrimagnetic MnO.

We present a computational materials design for defect-induced ferrimagnetic MnO. The magnetic properties of MnO containing Mn vacancies were investigated using first-principle calculations. For these electronic structure calculations, we employed a pseudo-self-interaction-corrected local density approximation (PSIC-LDA).

Dual defects of cation and anion in memristive nonvolatile memory of metal oxides.

The electrically driven resistance change of metal oxides, called bipolar memristive switching, is a fascinating phenomenon in the development of next-generation nonvolatile memory alternatives to flash technology. However, our understanding of the nature of bipolar memristive switching is unfortunately far from comprehensive, especially the relationship between the electrical transport and the local nonstoichiometry. Here we demonstrate that the coexistence of anion and cation defects is critical to the transport properties of NiO, one of the most promising memristive oxides, by utilizing first-principles calculations.

A density functional theory study of self-regenerating catalysts LaFe(1-x)M(x)O(3-y) (M = Pd, Rh, Pt).

Periodic density functional theory was used to investigate the stability and electronic structures of precious-metal atoms in the vicinity of LaFe(1-x)M(x)O(3) (M = Pd, Rh, Pt) perovskite catalyst surfaces. It was found that the surface segregation of Pd and Pt is significantly stabilized by the introduction of O vacancies, whereas the solid-solution phase is favorable for Rh, suggesting an important role of O vacancies in the self-regeneration of Pd and Pt. On the basis of the results, we propose a possible scenario for the self-regeneration of the precious metal in the perovskite catalyst.

Valence control of α-rhombohedral boron by electronic doping.

It was previously predicted that doping Li into semiconducting boron (α-rhombohedral) brought metallic character to the matrix and possibility a high-T(c) superconductor. However, experiments show that Li doping of α-rhombohedral boron is difficult. In this paper, the potential for Li doping of boron is re-examined using the ab initio pseudopotential method.

Ferromagnetism and Curie temperature of Vanadium-doped nitrides.

Electronic structures, exchange interaction mechanism between magnetic ions and Curie temperature of Vanadium-doped nitrides (AlN, GaN, and InN) are studied within KKR-LSDA-CPA. It is found that the ferromagnetic super-exchange interaction mechanism is dominant at low concentrations of Vanadium, but the anti-ferromagnetic super-exchange interaction appears and reduces the stabilization of ferromagnetism at sufficiently high concentrations (x > 0.10), especially for Vanadium-doped AlN and Vanadium-doped GaN.