Tunneling Between Spin Triplet Molecular Organic Superconductors
H.I. Ha, J.I. Oh, J. Moser, M.J. Naughton
Department of Physics, Boston College, Chestnut Hill, MA 02467 USA
We present the first ever tunneling data between two organic superconductors. Current - voltage measurements were taken on a bicrystal of the molecular organic superconductor (TMTSF)2ClO4 (Tc=1.3K). Strong evidence for spin triplet pairing has accumulated recently for this class of materials. We interpret the resulting dI/dV conductance vs. bias as representing a S-I-N-I-S junction between two triplet superconductors ("TNT"). An enormous zero bias conductance peak likely due to Andreev bound states (possibly coupled with Josephson effect) is observed, as well as a clearly identified superconducting energy gap of 0.5 meV (2D=4.2kBTc). Magnetic field studies show a Zeeman effect which provides information on the direction of the order parameter d-vector. We discuss the relevance of these results to the pairing symmetry (p or f-wave) of this spin triplet superconductor. This work was supported by the NSF.
Pseudogap, field-induced SC-AFI transition and quantum critical spin fluctuations in two-dimensional organics
Kazushi Kanoda
Department of Applied Physics, University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan
A family of quasi-two-dimensional organic conductors, k-(ET)2X, span a phase diagram including superconducting (SC) phase and antiferromagnetic insulating (AFI) phase. In this conference, we present our NMR observation of the pseudogap behavior and field-induced SC-AFI transition in the marginal superconducting phase, to which access was made by deuterated k-(ET)2Cu[N(CN)2]Br. We also report that a doped Mott insulator, k-(ET)4Hg2.78Cl8, show quantum critical AF fluctuations in contrast to k-(ET)2X with half-filled band.
Anisotropic Superconductivity in Magnetic Field Induced Superconductors l-(BETS)2FexGa1-xCl4
S Ujia, C Terakuraa, T Terashimaa, T Yakabea, Y Teraia, Y Imanakaa, S Yasuzukaa, M Tokumotob, F Sakaic, A Kobayashid, H Tanakae, H Kobayashie, L Balicasf, J. S. Brooksf
aNational Institute for Materials Science, Tsukuba, Ibaraki 305-0003, Japan
bNational Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8568, Japan
cInstitute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
dResearch Centre for Spectrochemistry, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
eInstitute for Molecular Science, Okazaki, Aichi 444-8585, Japan
fNational High Magnetic Field Laboratory, Florida State University, Tallahassee FL 32306, USA
We have measured the reisistance of the organic conductors l-(BETS)2FexGa1-xCl4 and found the anisotropic feature of the critical fields.
Genuine Two Dimensional Electrons in Bechgaard Salts
W. Kanga, Y. J. Joa, Haeyong Kanga, O. H. Chunga
Dept. of Physics, Sunchon University, Sunchon 540-742, Korea
aDept. of Physics, Ewha Womans University, Seoul 120-750, Korea
We will present our comparative study of Bechgaard salts which have played a key role to develop the physics of quasi-one-dimensional electron systems. However, our recent investigations revealed that a genuine two dimensional electron system can also be realized in this system. Angular magnetoresistance (AMR) of (TMTSF)2FSO3 under 8.2 kbar showed oscillatory behavior just like as many other (TMTSF)2X salts. However, the peak positions could not be explained with Lebed resonance model but with Yamaji resonance model. The former has been successfully used to explain the AMR of (TMTSF)2X and the latter for two dimensional (ET)2X. Also supporting the idea is a pronounced peak structure observed both in bc and ac rotations when the magnetic field was nearly parallel to the conducting plane.