8,515 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
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
Charge modulation as fingerprints of phase-string triggered interference
Charge order appears to be an ubiquitous phenomenon in doped Mott insulators,
which is currently under intense experimental and theoretical investigations
particularly in the high cuprates. This phenomenon is conventionally
understood in terms of Hartree-Fock type mean field theory. Here we demonstrate
a mechanism for charge modulation which is rooted in the many-particle quantum
physics arising in the strong coupling limit. Specifically, we consider the
problem of a single hole in a bipartite ladder. As a remnant of the
fermion signs, the hopping hole picks up subtle phases pending the fluctuating
spins, the so-called phase string effect. We demonstrate the presence of charge
modulations in the density matrix renormalization group solutions which
disappear when the phase strings are switched off. This form of charge
modulation can be understood analytically in a path-integral language, showing
that the phase strings give rise to constructive interferences leading to
self-localization. When the latter occurs, left- and right-moving propagating
modes emerge inside the localization volume and their interference is
responsible for the real space charge modulation.Comment: 14 pages, 10 figures. Comments on a followup paper by S. R. White, D.
J. Scalapino, and S. A. Kivelson (arXiv:1502.04403) adde
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