7,378 research outputs found
Nematic superconductivity in doped Bi2Se3 topological superconductors
Nematic superconductivity is a novel class of superconductivity characterized
by spontaneous rotational-symmetry breaking in the superconducting gap
amplitude and/or Cooper-pair spins with respect to the underlying lattice
symmetry. Doped Bi2Se3 superconductors, such as CuxBi2Se3, SrxBi2Se3, and
NbxBi2Se3, are considered as candidates for nematic superconductors, in
addition to the anticipated topological superconductivity. Recently, various
bulk probes, such as nuclear magnetic resonance, specific heat,
magnetotransport, magnetic torque, and magnetization, have consistently
revealed two-fold symmetric behavior in their in-plane magnetic-field-direction
dependence, although the underlying crystal lattice possesses three-fold
rotational symmetry. More recently, nematic superconductivity is directly
visualized using scanning tunneling microscopy and spectroscopy. In this short
review, we summarize the current researches on the nematic behavior in
superconducting doped Bi2Se3 systems, and discuss issues and perspectives.Comment: 20 pages (incl. 5 pages of reference list), 4 figures; Submitted for
the proceedings of Erice Workshop 2018 "Majorana Fermions and Topological
Materials Science". Small revisions are made on 14th Dec. Comments are
welcom
Finite Size Effects in Equations of State under non-trivial Boundary Conditions
We study free particles in a one-dimensional box with combinations of two
types of boundary conditions: the Dirichlet condition and a one-parameter
family of quasi-Neumann conditions at the two walls. We calculate energy
spectra approximately and obtain equations of state having the same
(one-dimensional) volume dependence as van der Waals equations of state. The
dependence of the equations of state is examined for particles obeying
Maxwell-Boltzmann, Bose-Einstein, or Fermi-Dirac statistics. Our results
suggest that the deviation from ideal gas may also be realized as finite size
effects due to the interaction between the particles and the walls.Comment: 18pages, 3 figure
High Pressure Effects on Superconductivity in the beta-pyrochlore Oxides AOs2O6 (A=K, Rb, Cs)
Recently new pyrochlore oxides superconductors AOs2O6 (A=K,Rb,Cs) were found
and we measured the pressure dependence of magnetization up to 1.2 GPa in order
to deduce the pressure effect of Tc in the three beta-pyrochlore oxides. It is
found that the initial pressure dependence of Tc is positive for all the
compounds. Only KOs2O6 exhibits a saturation in Tc at 0.56 GPa and the downturn
at higher pressureComment: 7 pages, 2 figure
Properties of the Nearly Free Electron Superconductor Ag5Pb2O6 Inferred from Fermi Surface Measurements
We measured the Fermi surface of the recently discovered superconductor
Ag5Pb2O6 via a de Haas-van Alphen rotation study. Two frequency branches were
observed and identified with the neck and belly orbits of a very simple, nearly
free electron Fermi surface. We use the observed Fermi surface geometry to
quantitatively deduce superconducting properties such as the in-plane and
out-of-plane penetration depths, the coherence length in the clean limit, and
the critical field; as well as normal state properties such as the specific
heat and the resistivity anisotropy.Comment: 2 pages, 1 figure, submitted to Physica C (M2S Proceedings
- …