Dynamical Screening and Superconducting State in Intercalated Layered Metallochloronitrides

An essential property of layered systems is the dynamical nature of the screened Coulomb interaction. Low energy collective modes appear as a consequence of the layering and provide for a superconducting-pairing channel in addition to the electron-phonon induced attractive interaction. We show that taking into account this feature allows to explain the high critical temperatures (Tc~26K) observed in recently discovered intercalated metallochloronitrides. The exchange of acoustic plasmons between carriers leads to a significant enhancement of the superconducting critical temperature that is in agreement with the experimental observations

Building a 3.5 m prototype interferometer for the Q & A vacuum birefringence experiment and high precision ellipsometry

We have built and tested a 3.5 m high-finesse Fabry-Perot prototype inteferometer with a precision ellipsometer for the QED test and axion search (Q & A) experiment. We use X-pendulum-double-pendulum suspension designs and automatic control schemes developed by the gravitational-wave detection community. Verdet constant and Cotton-Mouton constant of the air are measured as a test. Double modulation with polarization modulation 100 Hz and magnetic-field modulation 0.05 Hz gives 10^{-7} rad phase noise for a 44-minute integration.Comment: This draft has been presented in the 5th Edoardo Amaldi Conference on Gravitational Wave

Transport in the Heavy Fermion Superconductor UPt3

We report new theoretical results and analysis for the transport properties of superconducting UPt3 based on the leading models for the pairing symmetry. We use Fermi surface data and the measured inelastic scattering rate to show that the low-temperature thermal conductivity and transverse sound attenuation in the A and B phase of UPt3 are in excellent agreement with pairing states belonging to the two-dimensional orbital E2u representation.Comment: 2 pages, contribution at Int. Conf. LT-22, Helsinki, Finland, 4-11 Aug. 199

Josephson Current between Triplet and Singlet Superconductors

The Josephson effect between triplet and singlet superconductors is studied. Josephson current can flow between triplet and singlet superconductors due to the spin-orbit coupling in the spin-triplet superconductor but it is finite only when triplet superconductor has $L_z=-S_z=\pm 1$, where $L_z$ and $S_z$ are the perpendicular components of orbital angular momentum and spin angular momentum of the triplet Cooper pairs, respectively. The recently observed temperature and orientational dependence of the critical current through a Josephson junction between UPt$_3$ and Nb is investigated by considering a non-unitary triplet state.Comment: 4 pages, no figure

Quasiparticle Interactions for f2^2-Impurity Anderson Model with Crystalline-Electric-Field: Numerical Renormalization Group Study

The aspect of the quasiparticle interaction of a local Fermi liquid, the impurity version of f$^2$-based heavy fermions, is studied by the Wilson numerical renormalization group method. In particular, the case of the f$^2$-singlet crystalline-electric-field ground state is investigated assuming the case of UPt$_3$ with the hexagonal symmetry. It is found that the interorbital interaction becomes larger than the intraorbital one in contrast to the case of the bare Coulomb interaction for the parameters relevant to UPt$_3$. This result offers us a basis to construct a microscopic theory of the superconductivity of UPt$_3$ where the interorbital interactions are expected to play important roles.Comment: 9 pages, 5 figure

Super-ASTROD: Probing primordial gravitational waves and mapping the outer solar system

Super-ASTROD (Super Astrodynamical Space Test of Relativity using Optical Devices or ASTROD III) is a mission concept with 3-5 spacecraft in 5 AU orbits together with an Earth-Sun L1/L2 spacecraft ranging optically with one another to probe primordial gravitational-waves with frequencies 0.1 microHz - 1 mHz, to test fundamental laws of spacetime and to map the outer solar system. In this paper we address to its scientific goals, orbit and payload selection, and sensitivity to gravitational waves.Comment: 7 pages, 1 figure, presented to 7th International LISA Symposium, 16-20 June 2008, Barcelona; submitted to Classical and Quantum Gravity; presentation improve

A theory of new type of heavy-electron superconductivity in PrOs_4Sb_12: quadrupolar-fluctuation mediated odd-parity pairings

It is shown that unconventional nature of superconducting state of PrOs_4Sb_12, a Pr-based heavy electron compound with the filled-Skutterudite structure, can be explained in a unified way by taking into account the structure of the crystalline-electric-field (CEF) level, the shape of the Fermi surface determined by the band structure calculation, and a picture of the quasiparticles in f$^{2}$-configuration with magnetically singlet CEF ground state. Possible types of pairing are narrowed down by consulting recent experimental results. In particular, the chiral "p"-wave states such as p_x+ip_y is favoured under the magnetic field due to the orbital Zeeman effect, while the "p"-wave states with two-fold symmetery such as p_x can be stabilized by a feedback effect without the magnetic field. It is also discussed that the double superconducting transition without the magnetic field is possible due to the spin-orbit coupling of the "triplet" Cooper pairs in the chiral state.Comment: 12 pages, 2 figures, submitted to J. Phys.: Condens. Matter Lette

Effect of Spin-Orbit Interaction in Spin-Triplet Superconductor: Structure of d{\bf d}-vector and Anomalous 17^{17}O-NQR Relaxation in Sr2_2RuO4_4

Supposing the spin-triplet superconducting state of Sr$_2$RuO$_4$, the spin-orbit (SO) coupling associated with relative motion in Cooper pairs is calculated by extending the method for the dipole-dipole coupling given by Leggett in the superfluid $^{3}$He. It is shown that the SO coupling works only in the equal-spin pairing (ESP) state to make the pair angular momentum $\hbar{\vec L}$ and the pair spin angular momentum ${\rm i}{\vec d}\times{\vec d}^{*}$ parallel with each other. The SO coupling gives rise to the internal Josephson effect in a chiral ESP state as in superfluid A-phase of $^3$He with a help of an additional anisotropy arising from SO coupling of atomic origin which works to direct the {\bf d}-vector into $ab$-plane. This resolves the problem of the anomalous relaxation of $^{17}$O-NQR and the structure of {\bf d}-vector in Sr$_2$RuO$_4$.Comment: Accepted for publication in J. Phys. Soc. Jpn. vol.79 (2010), No.2 (February issue); 18 pages, 2 figure