15,314 research outputs found
Mutual Chern-Simons Theory of Spontaneous Vortex Phase
We apply the mutual Chern-Simons effective theory (Phys. Rev. B 71, 235102)
of the doped Mott insulator to the study of the so-called spontaneous vortex
phase in the low-temperature pseudogap region, which is characterized by strong
unconventional superconducting fluctuations. An effective description for the
spontaneous vortex phase is derived from the general mutual Chern-Simons
Lagrangian, based on which the physical properties including the diamagnetism,
spin paramagnetism, magneto-resistance, and the Nernst coefficient, have been
quantitatively calculated. The phase boundaries of the spontaneous vortex phase
which sits between the onset temperature and the superconducting
transition temperature , are also determined within the same framework.
The results are consistent with the experimental measurements of the cuprates.Comment: 12 pages, 8 figure
Slopes for higher rank Artin-Schreier-Witt Towers
We fix a monic polynomial over a finite field
of characteristic , and consider the
-Artin-Schreier-Witt tower defined by ; this
is a tower of curves , whose Galois group is canonically isomorphic to
, the degree unramified extension of
, which is abstractly isomorphic to as a
topological group. We study the Newton slopes of zeta functions of this tower
of curves. This reduces to the study of the Newton slopes of L-functions
associated to characters of the Galois group of this tower. We prove that, when
the conductor of the character is large enough, the Newton slopes of the
L-function asymptotically form a finite union of arithmetic progressions. As a
corollary, we prove the spectral halo property of the spectral variety
associated to the -Artin-Schreier-Witt tower. This
extends the main result in [DWX] from rank one case to the higher rank
case .Comment: 20 page
Lower Pseudogap Phase: A Spin/Vortex Liquid State
The pseudogap phase is considered as a new state of matter in the phase
string model of the doped Mott insulator, which is composed of two distinct
regimes known as upper and lower pseudogap phases, respectively. The former
corresponds to the formation of spin singlet pairing and the latter is
characterized by the formation of the Cooper pair amplitude and described by a
generalized Gingzburg-Landau theory. Elementary excitation in this phase is a
charge-neutral object carrying spin-1/2 and locking with a supercurrent vortex,
known as spinon-vortex composite. Here thermally excited spinon-vortices
destroy the phase coherence and are responsible for nontrivial Nernst effect
and diamagnetism. The transport entropy and core energy associated with a
spinon-vortex are determined by the spin degrees of freedom. Such a spontaneous
vortex liquid phase can be also considered as a spin liquid with a finite
correlation length and gapped S=1/2 excitations, where a resonancelike
non-propagating spin mode emerges at the antiferromagnetic wavevector with a
doping-dependent characteristic energy. A quantitative phase diagram in the
parameter space of doping, temperature, and magnetic field is determined.
Comparisons with experiments are also made.Comment: 22 pages, 12 figure
An equivalent expression of Z2 Topological Invariant for band insulators using Non-Abelian Berry's connection
We introduce a new expression for the Z2 topological invariant of band
insulators using non- Abelian Berry's connection. Our expression can identify
the topological nature of a general band insulator without any of the gauge
fixing problems that plague the concrete implementation of previous invariants.
The new expression can be derived from the "partner switching" of the Wannier
function center during time reversal pumping and is thus equivalent to the Z2
topological invariant proposed by Kane and Mele.Comment: 14 pages, 8 figure
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