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High-quality superconducting LaFeAsO$_{1-x}$F$_{x}$ thin films were grown on single crystalline LaAlO$_{3}$ substrates with critical temperatures (onset) up to 28 K. Resistive measurements in high magnetic fields up to 40 T reveal a paramagnetically limited upper critical field, $mu_{0}H_{c2}$(0) around 77 T and a remarkable steep slope of -7.5 T/K near $T_{c}$. From transport measurements we observed a weak link behavior in low magnetic fields and the evidence for a broad reversible regime.
We report conventional and time-resolved infrared spectroscopy on LaFeAsO$_{1-x}$F$_x$ superconducting thin films. The far-infrared transmission can be quantitatively explained by a two-component model including a conventional s-wave superconducting
Critical fields of four MgB2 thin films with a normal state resistivity ranging from 5 to 50 mWcm and Tc from 29.5 to 38.8 K were measured up to 28 T. Hc2(T) curves present a linear behavior towards low temperatures. Very high critical field values h
Orbital ordering has recently emerged as another important state in iron based superconductors, and its role for superconductivity as well as its connection to magnetic order and orthorhombic lattice distortion are heavily debated. In order to search
We have investigated the electronic structure of LaFeAsO$_{1-x}$F$_{x}$ (x = 0; 0.1; 0.2) by angle-integrated photoemission spectroscopy and local density approximation (LDA) based band structure calculations. The valence band consists of a low energ
The superconducting properties of LaFeAsO$_{1-x}$F$_{x}$ in conditions of optimal electron-doping are investigated upon the application of external pressure up to $sim 23$ kbar. Measurements of muon-spin spectroscopy and dc magnetometry evidence a cl