Related papers: Origin of superconductivity transition broadening …
The fluctuating diamagnetic magnetization Mfl at constant field H as a function of temperature and the isothermal magnetization Mfl vs H are measured in MgB2, above the superconducting transition temperature. The expressions for Mfl in…
It is shown that the transition to the low temperature superconducting state in a 3D metal at high magnetic field is smeared dramatically by thermal fluctuation of the superconducting order parameter. The resulting superconducting-to-normal…
The superconducting phase diagram of MgB2 was determined from magnetization, magneto-transport and the first single-crystal specific heat measurements. A zero-temperature in-plane coherence length of 8 nm is determined. The superconducting…
The field dependence of the magnetization above the transition temperature Tc in MgB₂ is shown to evidence a diamagnetic contribution consistent with superconducting fluctuations reflecting both the σ and π bands. In…
The magnetic field dependent critical current density $j_c(B)$ of a MgB$_2$ bulk sample has been obtained by means of magnetization hysteresis measurements. The $j_c(B)$ curves at different temperatures demonstrate a crossover from single…
We report magnetic field dependent magnetization and microwave impedance measurements on a MgB2 superconductor prepared by high pressure synthesis. We find that the upper critical field is linearly dependent on temperature near Tc and the…
In-plane electrical transport properties of MgB2 single crystals grown under high pressure of 4-6 GPa and temperature of 1400-1700oC in Mg-B-N system have been measured. For all specimens we found sharp superconducting transition around…
According to the crystal structure of MgB$_{2}$ and band structure calculations quasi-two-dimensional (2D) boron planes are responsible for the superconductivity. We report on critical fields and resistance measurements of 30 nm thick…
We report the temperature- and magnetic-field-dependent resistivity of MgB2 sintered at high temperature and high pressure condition. The superconducting transition width for the resistivity measurement was about 0.4 K, and the low-field…
We study the origin of broadening of superconducting transition in sputtered Nb films. From simultaneous tunneling and transport measurements we conclude that the upper critical field Hc2 always corresponds to the bottom of transition R~0,…
The angular and temperature dependence of the upper critical field Hc2 in MgB2 was determined from torque magnetometry measurements on single crystals. The Hc2 anisotropy gamma_H was found to decrease with increasing temperature, in…
We have successfully prepared the MgB2 superconducting bulk and powdered materials by the method of combustion synthesis. The starting materials used in this study were powders of Mg and B. X-ray powder diffraction pattern was well assigned…
In this paper, we reported the structural properties and superconductivity of Mg(B1-xCx)2 compounds. Powder x-ray diffraction results indicate that the samples crystallize in a hexagonal AlB2-type structure. Due to the chemical activity of…
We report and analyze reversible magnetization measurements on a high quality MgB2 single crystal in the vicinity of the zero field transition temperature, T_c=38.83 K, at several magnetic fields up to 300 Oe, applied along the c-axis.…
The recent discovery that superconductivity occurs in several clean itinerant ferromagnets close to low temperature magnetic instabilities naturally invites an interpretation based on a proximity to quantum criticality. Here we report…
We demonstrate direct evidence of possible surface superconductivity on small, well-shaped MgB2 single crystals. Transport measurements in the range H < 1.6 Hc2^c, where Hc2^c is the bulk upper critical field for the c axis, show non-Ohmic…
The recently-discovered MgB2 super-conductor has a transition temperature Tc approaching 40K, placing it intermediate between the families of low and high temperature super-conductors (LTS and HTS). In practical applications,…
Superconducting transition, defined as vanishing of the resistivity, under a magnetic field in a clean bulk type II superconductor with weak sample disorder is believed to be a reflection of freezing of the vortex liquid to a kind of vortex…
We synthesized single crystalline and policrystalline MgB_2 under ambient pressures. The single crystals of MgB_2 were of good quality, where the crystal structure refinements were successfully converged with R = 0.020. The specific heat of…
We studied the influence of sample preparation and defects in the superconducting properties samples using atomic ratios of Mg:B=1:1 and Mg:B=1:2. Samples were characterized by SEM, and XRD, and the magnetization properties were examined in…