Electronic phase separation in the slightly underdoped iron pnictide superconductor Ba1-xKxFe2As2.

Suppression of the structural phase transition and lattice softening in slightly underdoped Ba1-xKxFe2As2 with electronic phase separation

Doping evolution of the anisotropic upper critical fields in the iron-based superconductor Ba1−xKxFe2As2

In-plane resistivity measurements as a function of temperature and magnetic field up to 35 T with precise orientation within the crystallographic ac plane were used to study the upper critical field Hc2 of the holedoped iron-based superconductor Ba1−xKxFe2As2. Compositions of the samples studied spanned from underdoped x=0.17 (Tc=12 K) and x=0.22 (Tc=20 K), both in the coexistence range of stri...

Observation of the Josephson effect in Pb/Ba1-xKxFe2As2 single crystal junctions.

We have fabricated c-axis Josephson junctions on single crystals of Ba1-xKxFe2As2 by using Pb as the counterelectrode in two geometries, planar and point contact. Junctions in both geometries show resistively shunted junction I-V curves below the T{C} of the counterelectrode. Microwave induced steps were observed in the I-V curves, and the critical currents are suppressed with an in-plane magne...

Doping evolution of the anisotropic upper critical fields in the iron-based superconductor Ba1â‹TMxKxFe2As2

In-plane resistivity measurements as a function of temperature and magnetic field up to 35 T with precise orientation within the crystallographic ac plane were used to study the upper critical field Hc2 of the holedoped iron-based superconductor Ba1−xKxFe2As2. Compositions of the samples studied spanned from underdoped x=0.17 (Tc=12 K) and x=0.22 (Tc=20 K), both in the coexistence range of stri...

Unusual doping dependence of the electronic structure and coexistence of spin-density-wave and superconductor phases in single crystalline Sr1-xKxFe2As2.

The nature of the spin-density wave (SDW) and its relation with superconductivity are crucial issues in the newly discovered iron-pnictide superconductors. Particularly, it is unclear whether the superconducting phase and SDW are truly exclusive from each other. We here report splittings of the band structures in Sr1-xKxFe2As2 (x=0, 0.1, 0.18), and their unusual doping dependence. Our data on s...