13,574 research outputs found
Topological Hall Effect in Inhomogeneous Superconductors
We propose a possible mechanism of topological Hall effect in inhomogeneous
superconducting states. In our scenario, the Berry phase effect associated with
spatially modulated superconducting order parameter gives rise to a fictitious
Lorentz force acting on quasiparticles. In the case of the
Fulde-Ferrell-Larkin-Ovchinnikov state, the topological Hall effect is detected
by applying an electromagnetic wave with a tuned wave number on a surface of
the system.Comment: 4 page
Angular Fulde-Ferrell-Larkin-Ovchinnikov state in cold fermion gases in a toroidal trap
We study the possibility of angular Fulde-Ferrell-Larkin-Ovchinnikov (FFLO)
state, in which the rotation symmetry is spontaneously broken, in population
imbalanced fermion gases near the BCS-BEC crossover. We investigate the
superfluid gases at low temperatures on the basis of the Bogoliubov-de Gennes
equation, and examine the stability against thermal fluctuations using the
T-matrix approach beyond the local-density approximation (LDA). We find that
the angular FFLO state is stabilized in the gases confined in the toroidal trap
but not in the harmonic trap. The angular FFLO state is stable near the BCS-BEC
crossover owing to the formation of pseudogap. Spatial dependences of number
density and local population imbalance are shown for an experimental test.Comment: final version for publication in Phys. Rev. B Rapid Communicatio
Theory of the striped superconductor
We define a distinct phase of matter, a "pair density wave" (PDW), in which
the superconducting order parameter varies periodically as a function of
position such that when averaged over the center of mass position, all
components of vanish identically. Specifically, we study the simplest,
unidirectional PDW, the "striped superconductor," which we argue may be at the
heart of a number of spectacular experimental anomalies that have been observed
in the failed high temperature superconductor, La BaCuO. We
present a solvable microscopic model with strong electron-electron interactions
which supports a PDW groundstate. We also discuss, at the level of Landau
theory, the nature of the coupling between the PDW and other order parameters,
and the origins and some consequences of the unusual sensitivity of this state
to quenched disorder.Comment: 16 pages, 3 figures, 1 table; Journal ref. adde
Topological exciton condensate of imbalanced electrons and holes
I study the effects of particle-hole imbalance on the exciton superfluid
formed in a topological insulator thin-film and obtain the mean-field phase
diagram. At finite imbalance a spatially modulated condensate is formed, akin
to the Fulde-Ferrel-Larkin-Ovchinikov state in a superconductor, which preempts
a first-order transition from the uniform condensate to the normal state at low
temperatures. The imbalance can be tuned by changing the chemical potential at
the two surfaces separately or, alternatively, by an asymmetric application of
Zeeman fields at constant chemical potential. A vortex in the condensate
carries a precisely fractional charge half of that of an electron. Possible
experimental signatures for realistic parameters are discussed.Comment: 4 pages, 4 figures; (v2) Figures (especially Fig. 4) are improved;
Fig. 1 now shows the transition lines correctly (results are the same as
before); Text is updated and typos corrected; References are updated and
added. To appear in PR
Fate of the inert three-flavor, spin-zero color-superconducting phases
I investigate some of the inert phases in three-flavor, spin-zero
color-superconducting quark matter: the CFL phase (the analogue of the B phase
in superfluid ), the A and A* phases, and the 2SC and sSC phases. I
compute the pressure of these phases with and without the neutrality condition.
It is shown that the 2SC phase is identical to the A* phase up to a color
rotation. The CFL phase is the energetically favored phase except for a small
region of intermediate densities where the 2SC/A* phase is favored.Comment: 9 pages, 1 figure; the version accepted to publish in PR
Fermi-liquid effects in the Fulde-Ferrell-Larkin-Ovchinnikov state of two-dimensional d-wave superconductors
We study the effects of Fermi-liquid interactions on quasi-two-dimensional
d-wave superconductors in a magnetic field. The phase diagram of the
superconducting state, including the periodic Fulde-Ferrell-Larkin-Ovchinnikov
(FFLO) state in high magnetic fields, is discussed for different strengths of
quasiparticle many-body interactions within Landau's theory of Fermi liquids.
Decreasing the Fermi-liquid parameter causes the magnetic spin
susceptibility to increase, which in turn leads to a reduction of the FFLO
phase. It is shown that a negative results in a first-order phase
transition from the normal to the uniform superconducting state in a finite
temperature interval. Finally, we discuss the thermodynamic implications of a
first-order phase transition for CeCoIn.Comment: published version; removed direct comparison with experiment for the
upper critical field, as required by the referee
Crystalline chiral condensates off the tricritical point in a generalized Ginzburg-Landau approach
We present an extensive study on inhomogeneous chiral condensates in QCD at
finite density in the chiral limit using a generalized Ginzburg-Landau (GL)
approach. Performing analyses on higher harmonics of one-dimensionally (1D)
modulated condensates, we numerically confirm the previous claim that the
solitonic chiral condensate characterized by Jacobi's elliptic function is the
most favorable structure in 1D modulations. We then investigate the possibility
of realization of several multidimensional modulations within the same
framework. We also study the phase structure far away from the tricritical
point by extending the GL functional expanded up to the eighth order in the
order parameter and its spatial derivative. On the same basis, we explore a new
regime in the extended GL parameter space and find that the Lifshitz point is
the point where five critical lines meet at once. In particular, the existence
of an intriguing triple point is demonstrated, and its trajectory consists of
one of those critical lines.Comment: 17 pages, 20 eps figures; (v2) corrected an error in computation of
eighth order coefficients; (v3) typos corrected, version to appear in Phys.
Rev.
Vortex tilt modulus in Fulde-Ferrell-Larkin-Ovchinnikov state
Vortex tilt response in Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) vortex
lattice is theoretically examined as a probe reflecting the spatial structure
of this state. In the FFLO state with nodal planes perpendicular to the
magnetic field in a quasi 2D material under a parallel field, the tilt modulus
E_{2} {\it of the nodal planes} decreases as the paramagnetic effect is
effectively enhanced, and this reduction of E_{2} in turn reduces the vortex
tilt modulus. This reduction of vortex tilt modulus, more remarkable in more
anisotropic systems, accompanying the FFLO transition may be an origin of the
monotonous reduction of sound velocity detected upon cooling in a ultrasound
measurement for CeCoIn5.Comment: 14 pages, 5 figures. Accepted for publication in Phys. Rev.
Attractive Fermi gases with unequal spin populations in highly elongated traps
We investigate two-component attractive Fermi gases with imbalanced spin
populations in trapped one dimensional configurations. The ground state
properties are determined within local density approximation, starting from the
exact Bethe-ansatz equations for the homogeneous case. We predict that the
atoms are distributed according to a two-shell structure: a partially polarized
phase in the center of the trap and either a fully paired or a fully polarized
phase in the wings. The partially polarized core is expected to be a superfluid
of the FFLO type. The size of the cloud as well as the critical spin
polarization needed to suppress the fully paired shell, are calculated as a
function of the coupling strength.Comment: Final accepted versio
Fully developed triplet proximity effect
We present a model for fully developed triplet proximity effect in
superconductor-ferromagnet heterostructures.
Within the circuit-theory approximation, we evaluate the Green's functions,
the density of states, and the Josephson current that depend essentially on the
magnetization configuration.Comment: 4 pages, 4 figure
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