摘要 :
A novel apparatus has been developed to measure the transition temperature (T/sub c/) distribution and magnetic field profile of large superconducting films. Two techniques were used. The first one is an ac inductive method which ...
展开
A novel apparatus has been developed to measure the transition temperature (T/sub c/) distribution and magnetic field profile of large superconducting films. Two techniques were used. The first one is an ac inductive method which provides a contactless measurement of T/sub c/. The second technique employs a Hall device to measure magnetic field. Driven by two step motors, the measuring probe, either a two-coaxial-winding coil or a Hall sensor, can move over the sample on a polar plane. As the probe scans the sample step by step, various points on the sample are measured one by one. Experiments were carried out on a 30 mm diameter YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// thin-film. The T/sub c/ distribution and the surface profile of trapped magnetic field were obtained.
收起
摘要 :
We use powder neutron diffraction to study the spin and lattice structures of polycrystalline samples of nonsuperconducting PrFeAsO and superconducting PrFeAsO_(0.85)F_(0.15) and PrFeAsO_(0.85).We find that PrFeAsO exhibits abrupt...
展开
We use powder neutron diffraction to study the spin and lattice structures of polycrystalline samples of nonsuperconducting PrFeAsO and superconducting PrFeAsO_(0.85)F_(0.15) and PrFeAsO_(0.85).We find that PrFeAsO exhibits abrupt structural phase transitions at 153 K followed by static long-range antiferromagnetic order at 127 K. Both the structural distortion and magnetic order are similar to other rare-earth oxypnictides. Electron doping the system with either fluorine or oxygen deficiency suppresses the structural distortion and static long-range antiferromagnetic order, therefore placing these materials into the same class of FeAs-based superconductors.
收起
