To demonstrate the role played by the von Neumann entropy (vNE) spectra in quantum phase transitions we investigate the one-dimensional anisotropic SU(2) XXZ ⊗ spin-orbital model with negative exchange parameter. In the case of classical Ising orbital interactions we discover an unexpected novel phase with Majumdar-Ghosh-like spin-singlet dimer correlations triggered by spin-orbital entanglement (SOE) and having k 2 π = orbital correlations, while all the other phases are disentangled. For anisotropic XXZ orbital interactions both SOE and spin-dimer correlations extend to the antiferro-spin/alternating-orbital phase. This quantum phase provides a unique example of two coupled order parameters which change the character of the phase transition from first-order to continuous. Hereby we have established the vNE spectral function as a valuable tool to identify the change of ground state degeneracies and of the SOE of elementary excitations in quantum phase transitions. OPEN ACCESS RECEIVED

Organic field effect transistors (OFET) based on regioregular poly(3-hexylthiophene), P3HT, have been studied to investigate the substance properties of field-induced channel. The OFETs with bottom electrodes are fabricated by spin coating of P3HT solution on Si/SiO 2 substrate. The on/off ratio, carrier mobility, threshold voltage and transconductance of the OFETs coated with and without LiF are measured as the function of P3HT film thickness ranging from 20 -200 nm. The results indicate that the on/off ratio increased for thin films, though apparent mobility, threshold voltage and the transconductance decreased. The results are discussed in terms of the uniform distribution of charge carriers in the semiconductor region specified for OFETs.

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The pre-breakdown currents of a vacuum gap both just after spark conditioning of the electrodes and after exposure to a vacuum were measured in a vacuum of 3×10-5 Pa using a switching impulse voltage. It was found that the exposure reduced the field emission current and that this reduction became greater with the exposure time. The reduction in the field emission current is considered to be the result of an increase in the work function due to adsorption of residual gases on the electrode surfaces. Current pulses were also observed to appear on the pre-breakdown currents measured after exposures of longer than 5 minutes.

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