Calculation of NMR Properties of Solitons in Superfluid 3He-A

Superfluid 3He-A has domain-wall-like structures, which are called solitons. We calculate numerically the structure of a splay soliton. We study the effect of solitons on the nuclear-magnetic-resonance spectrum by calculating the frequency shifts and the amplitudes of the soliton peaks for both longitudinal and transverse oscillations of magnetization. The effect of dissipation caused by normal-superfluid conversion and spin diffusion is calculated. The calculations are in good agreement with experiments, except a problem in the transverse resonance frequency of the splay soliton or in magnetic-field dependence of reduced resonance frequencies.Comment: 15 pages, 10 figures, updated to the published versio

Zinc Deficiency Symptoms of Beans

Zinc deficiency is common (2) on bean plants grown on calcareous Portneuf silt loam in the Magic Valley of southern Idaho. Ten pounds of zinc per acre every third year is recommended for prevention (4). Land leveling or deep plowing brings to the surface the highly calcareous subsoil and intensifies the zinc deficiency problem. Beans grown following sugar beets or high manure or phosphate fertilizer applications are more likely to exhibit zinc deficiency symptoms (4)

Condensation Energy and High Tc Superconductivity

From an analysis of the specific heat of one of the cuprate superconductors it is shown, that even if a large part of the experimental specific heat associated with the superconducting phase transition is due to fluctuations, this part must be counted when one tries to extract the condensation energy from the data. Previous work by Chakravarty, Kee and Abrahams, where the fluctuation part was subtracted, has resulted in an incorrect estimation of the condensation energy.Comment: 4 pages, 5 encapsulated Postscript figures, uses ReVTeX.st

Condensation energy in strongly coupled superconductors

We consider the condensation energy in superconductors where the pairing is electronic in origin and is mediated by a collective bosonic mode. We use magnetically-mediated superconductivity as an example, and show that for large spin-fermion couplings, the physics is qualitatively different from the BCS theory as the condensation energy results from the feedback on spin excitations, while the electronic contribution to the condensation energy is positive due to an ``undressing'' feedback on the fermions. The same feedback effect accounts for the gain of the kinetic energy at strong couplings.Comment: 4 pages, revtex 4, 3 eps figure

Periodic Vortex Structures in Superfluid 3He-A

We discuss the general properties of periodic vortex arrangements in rotating superfluids. The different possible structures are classified according to the symmetry space-groups and the circulation number. We calculate numerically several types of vortex structures in superfluid 3He-A. The calculations are done in the Ginzburg-Landau region, but the method is applicable at all temperatures. A phase diagram of vortices is constructed in the plane formed by the magnetic field and the rotation velocity. The characteristics of the six equilibrium vortex solutions are discussed. One of these, the locked vortex 3, has not been considered in the literature before. The vortex sheet forms the equilibrium state of rotating 3He-A at rotation velocities exceeding 2.6 rad/s. The results are in qualitative agreement with experiments.Comment: 13 pages, 7 figures, http://boojum.hut.fi/research/theory/diagram.htm

Nodes of the Gap Function and Anomalies in Thermodynamic Properties of Superfluid 3^3He

Departures of thermodynamic properties of three-dimensional superfluid $^3$He from the predictions of BCS theory are analyzed. Attention is focused on deviations of the ratios $\Delta(T=0)/T_c$ and $[C_s(T_c)-C_n(T_c)]/C_n(T_c)$ from their BCS values, where $\Delta(T=0)$ is the pairing gap at zero temperature, $T_c$ is the critical temperature, and $C_s$ and $C_n$ are the superfluid and normal specific heats. We attribute these deviations to the momentum dependence of the gap function $\Delta(p)$, which becomes well pronounced when this function has a pair of nodes lying on either side of the Fermi surface. We demonstrate that such a situation arises if the P-wave pairing interaction $V(p_1,p_2)$, evaluated at the Fermi surface, has a sign opposite to that anticipated in BCS theory. Taking account of the momentum structure of the gap function, we derive a closed relation between the two ratios that contains no adjustable parameters and agrees with the experimental data. Some important features of the effective pairing interaction are inferred from the analysis.Comment: 17 pages, 4 figure

Unconventional Vortices and Phase Transitions in Rapidly Rotating Superfluid ^{3}He

This paper studies vortex-lattice phases of rapidly rotating superfluid ^3He based on the Ginzburg-Landau free-energy functional. To identify stable phases in the p-Omega plane (p: pressure; Omega: angular velocity), the functional is minimized with the Landau-level expansion method using up to 3000 Landau levels. This system can sustain various exotic vortices by either (i) shifting vortex cores among different components or (ii) filling in cores with components not used in the bulk. In addition, the phase near the upper critical angular velocity Omega_{c2} is neither the A nor B phases, but the polar state with the smallest superfluid density as already shown by Schopohl. Thus, multiple phases are anticipated to exist in the p-Omega plane. Six different phases are found in the present calculation performed over 0.0001 Omega_{c2} <= Omega <= Omega_{c2}, where Omega_{c2} is of order (1- T/T_c) times 10^{7} rad/s. It is shown that the double-core vortex experimentally found in the B phase originates from the conventional hexagonal lattice of the polar state near Omega_{c2} via (i) a phase composed of interpenetrating polar and Scharnberg-Klemm sublattices; (ii) the A-phase mixed-twist lattice with polar cores; (iii) the normal-core lattice found in the isolated-vortex calculation by Ohmi, Tsuneto, and Fujita; and (iv) the A-phase-core vortex discovered in another isolated-vortex calculation by Salomaa and Volovik. It is predicted that the double-core vortex will disappear completely in the experimental p-T phase diagram to be replaced by the A-phase-core vortex for Omega >~ 10^{3} ~ 10^{4} rad/s. C programs to minimize a single-component Ginzburg-Landau functional are available at {http://phys.sci.hokudai.ac.jp/~kita/index-e.html}.Comment: 13 pages, 9 figure

The Interspersed Spin Boson Lattice Model

We describe a family of lattice models that support a new class of quantum magnetism characterized by correlated spin and bosonic ordering [Phys. Rev. Lett. 112, 180405 (2014)]. We explore the full phase diagram of the model using Matrix-Product-State methods. Guided by these numerical results, we describe a modified variational ansatz to improve our analytic description of the groundstate at low boson frequencies. Additionally, we introduce an experimental protocol capable of inferring the low-energy excitations of the system by means of Fano scattering spectroscopy. Finally, we discuss the implementation and characterization of this model with current circuit-QED technology.Comment: Submitted to EPJ ST issue on "Novel Quantum Phases and Mesoscopic Physics in Quantum Gases

A Theory for High-TcT_c Superconductors Considering Inhomogeneous Charge Distribution

We propose a general theory for the critical $T_c$ and pseudogap $T^*$ temperature dependence on the doping concentration for high-$T_c$ oxides, taking into account the charge inhomogeneities in the $CuO_2$ planes. The well measured experimental inhomogeneous charge density in a given compound is assumed to produce a spatial distribution of local $\rho(r)$. These differences in the local charge concentration is assumed to yield insulator and metallic regions, possibly in a stripe morphology. In the metallic region, the inhomogeneous charge density yields also spatial distributions of superconducting critical temperatures $T_c(r)$ and zero temperature gap $\Delta_0(r)$. For a given sample, the measured onset of vanishing gap temperature is identified as the pseudogap temperature, that is, $T^*$, which is the maximum of all $T_c(r)$. Below $T^*$, due to the distribution of $T_c(r)$'s, there are some superconducting regions surrounded by insulator or metallic medium. The transition to a superconducting state corresponds to the percolation threshold among the superconducting regions with different $T_c(r)$'s. To model the charge inhomogeneities we use a double branched Poisson-Gaussian distribution. To make definite calculations and compare with the experimental results, we derive phase diagrams for the BSCO, LSCO and YBCO families, with a mean field theory for superconductivity using an extended Hubbard Hamiltonian. We show also that this novel approach provides new insights on several experimental features of high-$T_c$ oxides.Comment: 7 pages, 5 eps figures, corrected typo

Optical symmetries and anisotropic transport in high-Tc superconductors

A simple symmetry analysis of in-plane and out-of-plane transport in a family of high temperature superconductors is presented. It is shown that generalized scaling relations exist between the low frequency electronic Raman response and the low frequency in-plane and out-of-plane conductivities in both the normal and superconducting states of the cuprates. Specifically, for both the normal and superconducting state, the temperature dependence of the low frequency $B_{1g}$ Raman slope scales with the $c-$axis conductivity, while the $B_{2g}$ Raman slope scales with the in-plane conductivity. Comparison with experiments in the normal state of Bi-2212 and Y-123 imply that the nodal transport is largely doping independent and metallic, while transport near the BZ axes is governed by a quantum critical point near doping $p\sim 0.22$ holes per CuO$_{2}$ plaquette. Important differences for La-214 are discussed. It is also shown that the $c-$ axis conductivity rise for $T\ll T_{c}$ is a consequence of partial conservation of in-plane momentum for out-of-plane transport.Comment: 16 pages, 8 Figures (3 pages added, new discussion on pseudogap and charge ordering in La214