Z. Hossain

High-temperature superconductivity in Eu 0.5 K 0.5 Fe 2 As 2

Subsequent to our recent report of SDW type transition at 190 K and antiferromagnetic order below 20 K in EuFe2As2, we have studied the effect of K-doping on the SDW transition at high temperature and AF order at low temperature. 50% K doping suppresses the SDW transition and in turn gives rise to high-temperature superconductivity below T_c = 32 K, as observed in the electrical resistivity, AC susceptibility as well as magnetization. A well defined anomaly in the specific heat provides additional evidence for bulk superconductivity.

Photoconducting state and its perturbation by electrostatic fields in oxide-based two-dimensional electron gas

The two-carrier transport model as proposed for the two-dimensional electron gas formed at the interfaces of oxide heterostructures is investigated by means of a combined perturbation of near ultra-violet radiation and electrostatic field, applied both separately and simultaneously. Comparison of the photo-response of the prototype systems such as the band insulator LaAlO3 and Mott insulator LaTiO3 films on TiO2 terminated SrTiO3 show remarkably similarities. Two types of non-equilibrium carriers are generated in each system, having a signature of a particular type of perturbation characterized by distinctly different relaxation process. While, the photo-conducting state diminishes in a stretched exponential manner, with a temperature dependent activation energy varying from few tens of meV to ~ 1 to 2 meV on lowering the temperature, and a relaxation time of several hours, the recovery from electrostatic gating occurs in milli-seconds time scale. An attempt is also made to explain the experimental observations using the ab-initio density functional calculations. The calculations show that the electronic transitions associated with near ultra-violet radiation emerge from bands located at ~ 2 eV above and below the Fermi energy, which are the Ti 3d states of the SrTiO3 substrate, and that from the AlO2 (TiO2) layers of the LaAlO3 (LaTiO3) films, respectively. The slow decay of the photo-current to the unperturbed state is explained in terms of the closely spaced Ti 3dxy states in the lower conduction band, which are manifested as flat bands (or localized states) in the band structure. Such localization leads to increased carrier life-times, through the energy-time relationship of the uncertainty principle.

Valence fluctuation in Ce2Co3Ge5 and crystal field effect in Pr2Co3Ge5

Polycrystalline samples of ternary rare earth germanides R

Magnetoelastic coupling induced magnetic anisotropy in Co2(Fe/Mn)Si thin films

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Signatures of spin-glass behaviour in PrIr2B2 and heavy fermion behaviour in PrIr2B2C

Co

Spin polarized carrier injection from full Heusler alloy Co2MnSi into superconducting NbN

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Quantum phase transition in the heavy-fermion compound Yb Ir 2 Si 2

Ge

Magnetic order in Pr 2 Pd 3 Ge 5 and possible heavy-fermion behavior in Pr 2 Rh 3 Ge 5

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Kondo scattering in δ -doped LaTiO 3 / SrTiO 3 interfaces: Renormalization by spin-orbit interactions

(R = La, Ce and Pr) have been prepared and investigated by means of magnetic susceptibility, isothermal magnetization, electrical resistivity and specific heat measurements. All these compounds crystallize in orthorhombic U

Doping dependent evolution of magnetism and superconductivity in Eu1?xKxFe2As2 (x?=?0?1) and temperature dependence of the lower critical field Hc1

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