Search

Magnetic measurements are used for investigating the prediction of half-metallic ferromagnetism in [Rb.sub.4][O.sub.6]. These measurements have not confirmed the predicted magnetic state, thus concluding that the mixed oxide does not show the predicted half-metallicity.

The article investigates the prediction of half-metallic ferromagnetism in Rb4O6 through magnetic measurements. The magnetic properties of Rb4O6 were measured using a superconducting quantum interference device. Samples of approximately 100 milligrams, fused in Suprasil tubes under a helium atmosphere were used for the analysis.

We present the synthesis of Co2FeGa Heusler nanowires and the results of our investigations on their three-dimensional (3D) electric and magnetic internal and external fields mapped by electron holographic tomography (EHT). These fields will be of great importance in next-generation nanomagnets integrated in spintronics and memory devices. The Co2FeGa nanowires with a L21 ordered structure are prepared by a SBA-15 silica-assisted method. The magnetic dipole-like stray fields of several Co2FeGa nanowires are revealed by holographically reconstructed phase images. Based on the measured magnetic phase shifts of an individual nanowire and its 3D reconstruction using EHT, we obtain an internal magnetic induction with a magnitude of 1.15 T and a nonmagnetic surface layer of 10 nm thickness. Furthermore, we also reconstruct the 3D distribution of the electrostatic potential of the same nanowire.

The development of new phases of matter at oxide interfaces and surfaces by extrinsic electric fields is of considerable significance both scientifically and technologically. Vanadium dioxide (VO2), a strongly correlated material, exhibits a temperature-driven metal-to-insulator transition, which is accompanied by a structural transformation from rutile (high-temperature metallic phase) to monoclinic (low-temperature insulator phase). Recently, it was discovered that a low-temperature conducting state emerges in VO2 thin films upon gating with a liquid electrolyte. Using photoemission spectroscopy measurements of the core and valence band states of electrolyte-gated VO2 thin films, we show that electronic features in the gate-induced conducting phase are distinct from those of the temperature-induced rutile metallic phase. Moreover, polarization-dependent measurements reveal that the V 3d orbital ordering, which is characteristic of the monoclinic insulating phase, is partially preserved in the gate-induced metallic phase, whereas the thermally induced metallic phase displays no such orbital ordering. Angle-dependent measurements show that the electronic structure of the gate-induced metallic phase persists to a depth of at least ∼40 Å, the escape depth of the high-energy photoexcited electrons used here. The distinct electronic structures of the gate-induced and thermally induced metallic phases in VO2 thin films reflect the distinct mechanisms by which these states originate. The electronic characteristics of the gate-induced metallic state are consistent with the formation of oxygen vacancies from electrolyte gating.