We systematically investigate the characteristics of an electrical oscillation observed in two-terminal vanadium dioxide ͑VO 2 ͒ devices. These oscillations are observed at room temperature in a simple electrical circuit without inductive components. The circuit is composed only of a dc voltage source, the VO 2 device, and a standard resistor connected in series with the device. We explain why the observed oscillations are a result of the percolative metal-to-insulator transition ͑MIT͒ of VO 2 and the coexistence of the metal and insulating phases. Specifically, oscillations are attributed to the construction and destruction of capacitive regions composed of regions of the semiconducting phase, ͑as dielectric material͒ and metallic phase electron carriers, induced by the MIT ͑as capacitor electrodes͒. Since the coexistence of these phases-and thus the capacitive regions-is destroyed by elevated temperature, the MIT oscillation is not explained in terms of significant heat input but rather in terms of a voltage-triggered effect. It is also discussed whether the current jump at the onset of the oscillations is driven by Mott physics or by Peierls physics relying on a structural phase transition. Furthermore, the electrical parameter space surrounding these oscillations is explored, and a generation window is identified. Within this generation window, the oscillation frequency can be continuously tuned by adjusting applied voltage or by an external circuit component, such as resistor or added capacitor. The frequency of oscillations can be increased up to Ͼ1 MHz.

In this letter, we report an observation of room temperature electrical oscillation in vanadium dioxide (VO2), a representative strongly correlated material showing a metal-insulator transition. An electric circuit for the oscillation is simply composed of a voltage source and two-terminal VO2 thin film device serially connected with a standard resistor. The systematic procedures where the oscillation occurred were explained based on the electrical relationship between the VO2 device and resistor, and the generation window of the oscillation was determined. In particular, the oscillation frequency could be controlled by adjusting an external voltage and increased up to >0.5MHz.

Although the general game-based training and the game-based CIMT both improved on static and dynamic balance ability, game-based CIMT had a larger effect on static balance control, weight-bearing symmetry, and side-to-side weight shift.

We have investigated the chemical distributions and the local electronic structure of potential diluted magnetic semiconductor Ge0.94Mn0.06 single crystals using scanning photoelectron microscopy (SPEM), x-ray absorption spectroscopy (XAS), and photoemission spectroscopy (PES). The SPEM image shows the stripe-shaped microstructures, which arise from the chemical phase separation between the Mn-rich and Mn-depleted phases. The Mn 2p XAS shows that the Mn ions in the Mn-rich region are in the divalent high-spin Mn2+ states but that they do not form metallic Mn clusters. The Mn 3d PES spectrum exhibits a peak centered at approximately 4 eV below E(F) and the negligible spectral weight near E(F). This study suggests that the observed ferromagnetism in Ge1-xMnx arises from the phase-separated Mn-rich phase.