95,476 research outputs found
Type-I superconductivity in noncentrosymmetric superconductor AuBe
The noncentrosymmetric superconductor AuBe have been investigated using the
magnetization, resistivity, specific heat, and muon-spin relaxation/rotation
measurements. AuBe crystallizes in the cubic FeSi-type B20 structure with
superconducting transition temperature observed at = 3.2 0.1 K.
The low-temperature specific heat data, (T), indicate a weakly-coupled
fully gapped BCS superconductivity with an isotropic energy gap
2 = 3.76, which is close to the BCS value of 3.52.
Interestingly, type-I superconductivity is inferred from the SR
measurements, which is in contrast with the earlier reports of type-II
superconductivity in AuBe. The Ginzburg-Landau parameter is = 0.4
1/. The transverse-field SR data transformed in the maximum
entropy spectra depicting the internal magnetic field probability distribution,
P(H), also confirms the absence of the mixed state in AuBe. The thermodynamic
critical field, , calculated to be around 259 Oe. The zero-field SR
results indicate that time-reversal symmetry is preserved and supports a
spin-singlet pairing in the superconducting ground state.Comment: 9 pages, 9 figure
Optimizing the catching of atoms or molecules in two-dimensional traps
Single-photon cooling is a recently introduced method to cool atoms and
molecules for which standard methods might not be applicable. We numerically
examine this method in a two-dimensional wedge trap as well as in a
two-dimensional harmonic trap. An element of the method is an optical dipole
box trapping atoms irreversibly. We show that the cooling efficiency of the
single-photon method can be improved by optimizing the trajectory of this
optical dipole box.Comment: 8 pages, 11 figures, improved version with corrected typos et
- …