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 $T_{v}$ and the superconducting transition temperature $T_{c}$, 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

Tunable Localization and Oscillation of Coupled Plasmon Waves in Graded Plasmonic Chains

The localization (confinement) of coupled plasmon modes, named as gradons, has been studied in metal nanoparticle chains immersed in a graded dielectric host. We exploited the time evolution of various initial wavepackets formed by the linear combination of the coupled modes. We found an important interplay between the localization of plasmonic gradons and the oscillation in such graded plasmonic chains. Unlike in optical superlattices, gradient cannot always lead to Bloch oscillations, which can only occur for wavepackets consisting of particular types of gradons. Moreover, the wavepackets will undergo different forms of oscillations. The correspondence can be applied to design a variety of optical devices by steering among various oscillations.Comment: Sumitted to Journal of Applied Physic

Luttinger-volume violating Fermi liquid in the pseudogap phase of the cuprate superconductors

Based on the NMR measurements on Bi$_2$Sr$_{2-x}$La$_x$CuO$_{6+\delta}$ (La-Bi2201) in strong magnetic fields, we identify the non-superconducting pseudogap phase in the cuprates as a Luttinger-volume violating Fermi liquid (LvvFL). This state is a zero temperature quantum liquid that does not break translational symmetry, and yet, the Fermi surface encloses a volume smaller than the large one given by the Luttinger theorem. The particle number enclosed by the small Fermi surface in the LvvFL equals the doping level $p$, not the total electron number $n_e=1-p$. Both the phase string theory and the dopon theory are introduced to describe the LvvFL. For the dopon theory, we can obtain a semi-quantitative agreement with the NMR experiments.Comment: The final version in PR