[{"type":"speech","title":"Thermodynamic and transport properties of the noncentrosymmetric superconductor LaBiPt","issued":{"date-parts":[["2007"]]},"author":[{"family":"Goll","given":"G."},{"family":"Marz","given":"M."},{"family":"Hamann","given":"A."},{"family":"Tomanic","given":"T."},{"family":"Grube","given":"K."},{"family":"Yoshino","given":"T."},{"family":"Takabatake","given":"T."}],"note":"71.Jahrestagung der Deutschen Physikalischen Gesellschaft und DPG Fr\u00fchjahrstagung des Arbeitskreises Festk\u00f6rperphysik, Fachverband Tiefe Temperaturen, Regensburg, 26.-30.M\u00e4rz 2007 Verhandlungen der Deutschen Physikalischen Gesellschaft, R.6, B.42(2007) TT 10.12 Internat.Conf.on Strongly Correlated Electron Systems (SCES'07), Houston, Tex., May 13-18, 2007","abstract":"Section Low Temperature Physics (TT)\nTuesday\ntion of the doping level.\nAt terahertz frequencies, we performed measurements in high magnetic \ufb01elds to suppress superconductivity below Tc. From the conductivity spectra we extract the quasiparticle scattering rate as a function\nof temperature, and compare its behavior in the superconducting and\nnormal states below Tc . We \ufb01nd a small but measurable optical magnetoresistance at all doping levels, and no signatures for the pseudogap.\nWe also discuss the applicability of \u201duniversal scaling laws\u201dto our data\non conductivity and penetration depth.\n15 min. break\nTT 10.8\nTue 11:30\nH18\nCharge modulation driven Fermi surface of Pb-Bi2201 \u2014\n\u00a8\n\u2022Lenart Dudy, Beate Muller, Alica Krapf, Helmut Dwelk,\nRalf-Peter Blum, Christoph Janowitz, and Recardo Manzke \u2014\n12489 Berlin\nDue to doping with lead it is well known that the about (1x5) superstructure of Bi cuprate superconductors will be suppressed. Nevertheless, a Fermi surface map of Bi2\u2212y P by Sr2\u2212x Lax CuO6+\u03b4 with x = 0.4\nand y = 0.4 determined by angular resolved photoemission (ARPES)\nrevealed additional Fermi surface (FS) features. Here a La content of x\n= 0.4 means optimum hole doping for a maximum value of Tc and for\na Pb amount of y = 0.4 one commonly expect complete suppression of\nthe superstructure. Low energy electron di\ufb00raction of these samples\nshowed no sign of a superstructure. Scanning tunnelling microscopy,\non the other hand, revealed directly two modulations of the electron\ndensity of much weaker amplitude, one long-range modulation of about\n(1x32) periodicity and a second of about (12x12). By taking into account the wave vectors and intensities of these two modulations the\ncorresponding Fermi surface has been simulated, which agrees strikingly good with the experimental one. The occurrence of modulations\nin these high-Tc superconductors will be further discussed.\nTT 10.9\nTue 11:45\nH18\nEnergy dependence of excitations near the Fermi surface\n\u00a8\nin Bi(Pb)-2212 and Bi(Pb)-2201 \u2014 \u2022B. Muller, L. Dudy, H.\nDwelk, A. Krapf, C. Janowitz, and R. Manzke \u2014 Humboldt Universit\u00a8t Berlin, Institut f\u00a8r Physik, Newtonstr. 15, 12489 Berlin\nIn Bi derived HTc -cuprates the question of how many excitations occur near the Fermi surface is not yet completely answered. There are\nhints that more than the two peaks derived from bilayer-splitting are\nhidden in the well-known peak-dip-hump structure [1,2]. In our group\nit was previously argued that an additional polarisation dependent\ndouble-peak structure arises in the one- and two-layer Bi-cuprate [2].\nIn Bi(Pb)-2201 this can be traced unequivocally since there are no superstructure or bilayer e\ufb00ects possibly concealing this excitation. In\nBi(Pb)-2212 the intensity ratio of the peak-dip-hump structure is energy dependent which could be a tool to uncover split excitations [1].\nIn this contribution the photon energy dependence of the excitations\nnear the Fermi energy of Bi(Pb)-2212 and Bi(Pb)-2201 is studied.\nLett. 89 (2002) 077003\nRev. B 63 (2001)R 100504; C. Janowitz, R. M\u00a8 ller, L. Dudy, A. Krapf,\nR. Manzke, C. Ast, H. H\u00a8chst, Europhys. Lett. 60 (2002) 615\nTT 10.10\nTue 12:00\nH18\nSTM local strucuture analysis of Pb-Bi2201 depending on the\n\u00a8\nAlica Krapf, Helmut Dwelk, Christoph Janowitz, and Recardo\ntonstr. 15, 12489 Berlin\nWith scanning tunneling microscopy (STM) we have performed a\ndetailed and systematic structural analysis of optimally lanthanum\ndoped single-layered bismuth cuprates, Bi2\u2212y P by Sr2\u2212x Lax CuO6+\u03b4\n(x = 0.4), as a function of the Pb content. As expected, the periodicity of the well-known (5 \u00d7 1) superstructure varies with increasing the\namount of Pb. For about y = 0.4 the superstructure is almost suppressed but, unexpectedly, new modulations occur in the electron den-\nsity which might in\ufb02uence the electronic properties of these cuprates.\nIn addition, this could a\ufb00ect the charge transfer between the carrier\nreservoir (BiO-SrO) and the CuO2 plane as suggested for Pb-Bi2212\nby Shi et al.[1].\n[1] L. Shi et al., J. Phys.: Condens. Matter 13, 5195 (2001)\nTT 10.11\nTue 12:15\nH18\nMagnetic \ufb01eld dependence of the superconducting gap node\ntopology in non-centrosymmetric CePt3 Si \u2014 \u2022Ilya Eremin1,2\nand James Annett3 \u2014 1 Max-Planck-Institut f\u00a8r Physik Komplexer\nLaboratory, University of Bristol, Tyndall\nNon-centrosymmetric superconductors, such as CePt3 Si and Li2 PtB2 ,\nare believed to have a line node in the energy gap arising from coexistence of s-wave and p-wave pairing. Using as an example CePt3 Si we\nshow that a weak c-axis magnetic \ufb01eld will remove this line node, since\nit has no topological stability against time-reversal symmetry breaking\nperturbations. Conversely a \ufb01eld in the a \u2212 b plane is shown to remove\nthe line node on some regions of the Fermi surface, while bifurcating the line node in other directions, resulting in two \u2019boomerang\u2019-like\nshapes. These line node topological changes are predicted to be observable experimentally in the low temperature heat capacity.\nTT 10.12\nTue 12:30\nH18\nThermodynamic and Transport Properties of the Noncentrosymmetric Superconductor LaBiPt \u2014 \u2022Gernot Goll1 ,\nKarlsruhe, Institut f\u00a8r Festk\u00a8rperphysik, 76021 Karlsruhe \u2014\n3 Hiroshima University, Higashi-Hiroshima, Japan\nNoncentrosymmetric superconductors have attracted considerable interest in recent years. The lack of an inversion center of the crystal lattice makes unconventional pairing symmetries feasible. Even\nmixed superconducting states consisting of singlet and triplet states\nare possible. We report on the observation of superconductivity in the\nhalf-Heusler compound LaBiPt which crystallizes in the noncentrosymmetric cubic space group F\u00af\n43m. The crystal structure is composed of\nthree fcc sublattices for Pt, Bi, and La with the relative atomic coordinates (0,0,0), (1\/4,1\/4,1\/4), and (3\/4,3\/4,3\/4), respectively. LaBiPt\nbecomes superconducting below Tc \u2248 0.9 K as evidenced from measurements of the resistivity, magnetisation and speci\ufb01c heat. In\nview of a simpli\ufb01ed BCS model Tc \u223c TD exp (\u2212(N (0)V )\u22121 ) where\nN (0) \u223c m\u2217 n1\/3 is the electronic density of states at the EF , TD is\nthe Debye temperature, and V is the e\ufb00ective, attractive potential, is\nsurprisingly high because LaBiPt is a semimetal with very low chargecarrier concentrations n = 6 \u00b7 1018 cm\u22123 . The carrier concentration\nis still 1-2 orders of magnitude lower than in the classical low-carrierdensity superconductors GeTe and SnTe and comparable to that found\nin SrTiO3 .\nTT 10.13\nTue 12:45\nH18\nGinzburg-Landau theory of superconducting surfaces under\nKolacek4 , Ernst Helmut Brandt5 , and Tzong Jer Yang6 \u2014\n1 Faculty of Mathematics and Physics, Charles University, Ke Karlovu\n3, 12116 Prague 2, Czech Republic \u2014 2 Institute of Physics, Chemnitz\nUniversity of Technology, 09107 Chemnitz, Germany \u2014 3 Max Planck\nInstitute for the Physics of Complex Systems, Noethnitzer Str. 38,\n01187 Dresden, Germany \u2014 4 Institute of Physics, Academy of Sciences, Cukrovarnick\u00b4 10, 16253 Prague 6, Czech Republic \u2014 5 Max\nPlanck Institute for Metals Research, D-70506 Stuttgart, Germany\n\u2014 6 Department of Electrophysics, National Chiao-Tung University,\nHsinchu 300, Taiwan\nA boundary condition fo","kit-publication-id":"240067489"}]