100 research outputs found
Interlayer spin-singlet pairing induced by magnetic interactions in an antiferromagnetic superconductor
It is shown that interlayer spin-singlet Cooper pairing is induced by
magnetic interactions in a metallic antiferromagnet of stacked conductive
layers in which each layer is ferromagnetically polarized and they order
antiferromagnetically in stacking direction. As a result, the antiferromagnetic
long-range order and superconductivity coexist at low temperatures. It is shown
that T_AF > T_c except for in a very limited parameter region unless T_AF = 0,
where T_AF and T_c denote the antiferromagnetic and superconducting transition
temperatures, respectively. It is found that the exchange field caused by the
spontaneous staggered magnetization does not affect superconductivity at all,
even if it is very large. The resultant superconducting order parameter has a
horizontal line node, and is isotropic in spin space in spite of the anisotropy
of the background magnetic order. We discuss the possible relevance of the
present mechanism to the antiferromagnetic heavy fermion superconductors
UPd_2Al_3 and CePt_3Si.Comment: 5 pages, 3 figures, in revtex
Field-asymmetric transverse magnetoresistance in a nonmagnetic quantum-size structure
A new phenomenon is observed experimentally in a heavily doped asymmetric
quantum-size structure in a magnetic field parallel to the quantum-well layers
- a transverse magnetoresistance which is asymmetric in the field (there can
even be a change in sign) and is observed in the case that the structure has a
built-in lateral electric field. A model of the effect is proposed. The
observed asymmetry of the magnetoresistance is attributed to an additional
current contribution that arises under nonequilibrium conditions and that is
linear in the gradient of the electrochemical potential and proportional to the
parameter characterizing the asymmetry of the spectrum with respect to the
quasimomentum.Comment: 10 pages, 5 figures. For correspondence, mail to
[email protected]
Hybridization and interference effects for localized superconducting states in strong magnetic field
Within the Ginzburg-Landau model we study the critical field and temperature
enhancement for crossing superconducting channels formed either along the
sample edges or domain walls in thin-film magnetically coupled superconducting
- ferromagnetic bilayers. The corresponding Cooper pair wave function can be
viewed as a hybridization of two order parameter (OP) modes propagating along
the boundaries and/or domain walls. Different momenta of hybridized OP modes
result in the formation of vortex chains outgoing from the crossing point of
these channels. Near this crossing point the wave functions of the modes merge
giving rise to the increase in the critical temperature for a localized
superconducting state. The origin of this critical temperature enhancement
caused by the wave function squeezing is illustrated for a limiting case of
approaching parallel boundaries and/or domain walls. Using both the variational
method and numerical simulations we have studied the critical temperature
dependence and OP structure vs the applied magnetic field and the angle between
the crossing channels.Comment: 12 pages, 13 figure
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