A5101851443- Organic and Molecular Conductors Research
- Magnetism in coordination complexes
- Physics of Superconductivity and Magnetism
- Solid-state spectroscopy and crystallography
- Semantic Web and Ontologies
- Quantum and electron transport phenomena
- N-Heterocyclic Carbenes in Organic and Inorganic Chemistry
- Inorganic Fluorides and Related Compounds
- Advanced Condensed Matter Physics
- Molecular Junctions and Nanostructures
- X-ray Diffraction in Crystallography
- Service-Oriented Architecture and Web Services
- Crystallization and Solubility Studies
- Rare-earth and actinide compounds
- Iron-based superconductors research
- Crystallography and molecular interactions
- Data Quality and Management
- Advanced Database Systems and Queries
- French Urban and Social Studies
- Fullerene Chemistry and Applications
- Advanced NMR Techniques and Applications
- Biomedical Text Mining and Ontologies
- Cultural Insights and Digital Impacts
- High-pressure geophysics and materials
- Data Mining Algorithms and Applications
NOSM University
2020-2025
University of British Columbia
2025
University of Alberta
2020-2025
Institut national de recherche en informatique et en automatique
2012-2024
University of California, Los Angeles
2024
NOAA Oceanic and Atmospheric Research
2024
Université Grenoble Alpes
2008-2023
University of Geneva
2011-2023
Ghent University Hospital
2022
Canadian Parks and Wilderness Society
2022
2014 Nous avons observé le phénomène de supraconductibilité dans conducteur organique quasi-uni- dimensionnel di-(tétraméthyltétraselénofulvalène)-hexafluorophosphate, (TMTSF)2PF6, par mesures résistives sous pression hydrostatique 12 kbar à une température 0,9 K. présentons aussi l'effet champs magnétiques perpendiculaires l'axe des chaines.Abstract.2014 Superconductivity has been observed by resistive measurements in the quasi-one dimensional organic conductor...
Abstract This review attempts to present the most salient developments of research on organic conductors and superconductors during past 10 years. A theoretical introduction treats instabilities quasi-one-dimensional electron systems associated precursor effects which are relevant experimental results conductors. We then describe characterization by their transport, optical magnetic properties. Finally, two sections devoted investigation low temperature instabilities: lattice instability in...
This paper presents theoretical considerations of a new kind insulating phase which has recently been theoretically predicted but as yet not found experimentally. is expected to occur when semiconductors with very small band gap or semimetals overlap are cooled sufficiently low temperature. The present first develops BCS-like theory the ground state and analyzes nature response general perturbation, from collective modes (of sound-like nature), static magnetic field, conductivity calculated....
The upper temperature for superconductivity in organic conductors has increased from 1 kelvin 1980, when the phenomenon was discovered quasi—one-dimensional cation radical salt tetramethyltetraselenafulvalene phosphorus heptafluoride to 12 a new series of salts that show nearly two-dimensional electronic properties. These superconductors are attracting interest because wide range phenomena they exhibit, including competition between various ground states, influence magnetic field on...
We have performed in-plane transport measurements on the two-dimensional organic salt kappa-(BEDT-TTF)(2)Cu[N(CN)(2)]Cl. A variable (gas) pressure technique allows for a detailed study of changes in conductivity through insulator-to-metal transition. identify four different regimes as function and temperature (corresponding to insulating, semiconducting, "bad metal," strongly correlated Fermi-liquid behaviors). Marked hysteresis is found transition region, which displays complex physics that...
This paper presents the frequency dependance of proton spin-lattice relaxation time T1 at several temperatures and pressures in TTF-TCNQ(D4) TTF(D4)-TCNQ. It is shown that only backward (q = 2 kF) forward 0) scatterings contribute to nuclear induced by modulation hyperfine field these one-dimensional conductors. At medium fields, H 0 ~ 30 kOe, dependence originates from diffuse character spin density wave excitations around q 0, leading T1-1 αH0- 1/2 . The enhancement -1, low limited...
We report a Hall effect and magnetoresistance study of sin- gle crystals the organic superconductor tetramethyl-tetraselenafulvalinium hexafluorophosphate, (TMTSF${)}_{2}$${\mathrm{PF}}_{6}$, under hydrostatic pressure at temperatures down to 0.5 K in magnetic fields up 25 T. There is clear evidence for quantized effect, with plateaus labeled by integers n=5 1, 17 A new field-induced phase transition very resistive state occurs 18 believe that this ``n=0'' spin-density-wave predicted nesting theory.
We present the first $^{13}\mathrm{C}$ NMR measurements carried out in superconducting state of a two-dimensional organic single crystal. Spin lattice relaxation rate and Knight shift are reported for magnetic fields parallel perpendicular to conducting layers. For fields, is dominated by electronic excitations vortex cores. From field dependence ${({T}_{1})}^{\ensuremath{-}1}$ we obtain upper critical [${H}_{c2}(0)=10$ T]. In orientation, absence reveals existence lock-in state, where only...
Alignments represent correspondences between entities of two ontologies. They are produced from the ontologies by ontology matchers. In order for matchers to exchange alignments and applications manipulate alignments, a minimal ag
2014 L'apparition d'une phase magnétique est observée en dessous de 3,5 K environ juste au-dessus la transition supraconductrice (Tc ~ 1 K) dans (TMTSF)2ClO4.L'état obtenu après un refroidissement rapide (~ 25 K/min.) a été caractérisé par des mesures l'amplitude et temps relaxation résonance nucléaire 77Se 1H.La température d'ordre ne dépend pratiquement pas du champ entre 10 65 kOe.Dans le même échantillon refroidi lentement l'ordre n'est plus observé 1,3 K. Les effets cyclages thermiques...
At low temperatures, dimensional metals are commonly found to exhibit superlattices incommensurate with the primitive lattice (periodic distortion coupled charge density waves, PLD — CDW). Transitions such states driven by strong electron phonon coupling and favoured particular forms of Fermi surfaces these metals. Experimental investigations structural distortions, changes in electronic structure around level produced CDW state, will be discussed for layered dichalcogenides, linear chain...
We have performed both in-plane resistivity, Hall effect, and specific heat measurements on the thermoelectric cobalt oxide ${\mathrm{Ca}}_{3}{\mathrm{Co}}_{4}{\mathrm{O}}_{9}$. Four distinct transport regimes are found as a function of temperature, corresponding to low temperature insulating one up ${T}_{\mathit{min}}\ensuremath{\approx}63\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, strongly correlated Fermi liquid ${T}^{*}\ensuremath{\approx}140\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, with...
We present 13C NMR measurements carried out under pressure and between 10 300 K on a single crystal of the organic superconductor κ-(ET)2Cu[N(CN)2]Br. Under pressure, large variation Knight shift is interpreted as presence electronic correlations. estimate U/W ratio to be order unity. As regards temperature, we report enhancement 1/T1T drop near 50 K. These anomalies tend disappear all properties becoming more usual for metal. results are seen similar those observed in high-Tc...
2014 Nous présentons une étude de l'effet Hall effectuée à basse température dans (TMTSF)2ClO4 après refroidissement lent, jusqu'à un champ 80 kOe placé perpendiculairement au plan (a-b).La très faible résistance dépendant linéairement du magnétique 40 indique l'existence d'un conducteur surface Fermi quasi-planaire et densité porteurs correspondant la stoechiométrie.La croissance brutale constante obser- vée en élevé transition vers état semi-métallique.Les marches plateaux observés l'état...
$(\mathrm{TMTSF}{)}_{2}{\mathrm{ClO}}_{4}$ is a quasi-one-dimensional organic conductor and superconductor with ${T}_{c}=1.4\text{ }\text{ }\mathrm{K}$, one of at least two Bechgaard salts observed to have upper critical fields far exceeding the paramagnetic limit. Nevertheless, $^{77}\mathrm{Se}$ NMR Knight shift low reveals decrease in spin susceptibility ${\ensuremath{\chi}}_{s}$ consistent singlet pairing. The field dependence spin-lattice relaxation rate 100 mK exhibits sharp crossover...
2014 Nous avons effectué des mesures de la chaleur spécifique du supraconducteur organique (TMTSF)2ClO4 entre 0,4 et 2 K. La forte anomalie contribution électronique à observée 1,22 K a été attribuée l'établissement l'ordre tridimen- sionnel.En outre très dépendance en champ magnétique au-dessus n'est pas caractéristique d'un conducteur usuel dans un état normal.Un 63 kOe appliqué suivant l'axe c* monocristaux stabilise fondamental système présentant une faible valeur densité d'états au...
2014 L'existence d'ondes de densité spins dans la phase semiconductrice (TMTSF)2PF6 est confirmée par disparition du signal résonance magnétique nucléaire 77Se et l'élargissement des protons.Les modes collectifs l'onde commensurable avec le réseau contribuent notablement à relaxation spin-réseau protons.Nous suggérons, en outre, une explication très faible valeur l'am- plitude spin, basée sur coexistence deux divergences ce conducteur unidimen- sionnel : supraconductivité magnétisme.
High-resolution photoemission experiments have been carried out on one-dimensional organic conductors in their normal state. In contrast to usual metals, the spectral function vanishes at Fermi level and no edge is detectable. These results are consistent with a Luttinger description an exponent α of larger than 1 found. This result corroborates recent nuclear-magnetic-resonance experiments. Such large correlation shows that 1D Hubbard model not appropriate strong long-range interactions...
Electric-field-dependent measurements are reported in the spin-density-wave state of organic conductor ${(\mathrm{TMTSF})}_{2}$N${\mathrm{O}}_{3}$. Nonlinearity appears longitudinal conductivity above a finite threshold field about 40 mV/cm. No temperature dependence is detectable up to at least half transition temperature. The excess smaller samples with lower resistance ratio. sliding mode might be responsible for observed electric-field-dependent response.
We report the pressure dependence of three phase transitions in TTF-TCNQ as determined by resistivity measurements. There is only one transition above 15 kbar, and we find a 4-kbar regime centered at 20 kbar where temperature peaks (the distortion ${T}_{d}=71$ K kbar), first order. suggest that there commensurate \ifmmode\times\else\texttimes\fi{}3 superlattice this resulting from an increase charge transfer to $\frac{2}{3}$.
New measurements of electrical conductivity along the b axis tetrathiafulvalenium-tetracyanoquinodimethanide (TTF-TCNQ) are combined with published results to provide a comprehensive summary including approximately 600 samples studied at 18 different laboratories. The magnitudes these measured conductivities do not necessitate assumption superconducting fluctuations or any other collective state in which exceeds limitations single-particle scattering. Since an adequate theory scattering for...