The phase diagram of the organic superconductor kappa-(ET)2Cu[N(CN)2]Cl has been accurately measured from 1H NMR and ac susceptibility techniques under helium gas pressure. domains stability antiferromagnetic superconducting orders in pressure vs temperature plane have determined. Both phases overlap through a first-order boundary that separates two regions inhomogeneous coexistence. curve merges with line metal-insulator transition which ends critical point at higher temperature. whole...

Using one- and two-dimensional NMR spectroscopy applied to ${}^{13}\mathrm{C}$ spin-labeled $(\mathrm{TMTTF}{)}_{2}{\mathrm{AsF}}_{6}$ $(\mathrm{TMTTF}{)}_{2}{\mathrm{PF}}_{6}$, we demonstrate the existence of an intermediate charge-ordered phase in TMTTF family charge-transfer salts. At ambient temperature, spectra are characteristic nuclei equivalent molecules. Below a continuous charge-ordering transition temperature ${T}_{\mathrm{co}}$, there is evidence for two inequivalent molecules...

The nature of the superconducting state in quasi-one-dimensional organic conductors has remained controversial since its discovery. Here we present results (77)Se NMR Knight shift (K(s)) experiments (TMTSF)(2)PF(6) under 7 kbar pressure with a magnetic field aligned along most conducting axis. We find no noticeable K(s) upon cooling through transition. Since directly probes spin susceptibility chi(s), fact that chi(s) remains unchanged transition strongly suggests spin-triplet superconductivity.

Prolonged storage ( approximately 2 years) or gentle heating (50-80 degrees C) of crystalline 2,5-dibromo-3,4-ethylenedioxythiophene (DBEDOT) affords a highly conducting, bromine-doped poly(3,4-ethylenedioxythiophene) (PEDOT), as confirmed by solid-state NMR, FTIR, CV, and vis-NIR spectroscopies. The novel polymerization (SSP) does not occur for 2,5-dichloro-3,4-ethylenedioxythiophene (DCEDOT), requires much higher temperature (>130 2,5-diiodo-3,4-ethylenedioxythiophene (DIEDOT). X-ray...

Recent developments in research into superconductivity organic materials are reviewed. In the epoch-defining quasi-one-dimensional TMTSF superconductors with T c ∼1 K, decreases monotonically increasing pressure, as do signatures of spin fluctuations normal state, providing good evidence for magnetically-mediated pairing. Upper critical fields exceed Zeeman-limiting field by several times, suggesting triplet pairing or a transition to an inhomogeneous superconducting state at high magnetic...

Significance The control of matter at the molecular scale is a key requirement for development smart materials and artificial machines. A challenging but promising platform in this emergent field science crystalline with components that experience motion structurally predetermined manner, such changes their state collective orientation suitably functionalized molecules may lead to useful thermal, dielectric, optical properties response external physical or chemical influences. Here, we...

Significance <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mtext>Sr</mml:mtext> </mml:mrow> <mml:mn>2</mml:mn> </mml:msub> <mml:mtext>RuO</mml:mtext> <mml:mn>4</mml:mn> </mml:math> is distinctive among unconventional superconductors, in that addition to exhibiting evidence for strong correlations, it stoichiometric and extremely clean. As a result, its electronic structure unusually well characterized, rendering an ideal platform...

$(\mathrm{TMTSF}{)}_{2}{\mathrm{ClO}}_{4}$ 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...

Subharmonic steps in the dc $I\ensuremath{-}V$ characteristics are reported model compound Nb${\mathrm{Se}}_{3}$, when subjected to combined and ac drives. The occur at currents which correspond frequencies ${\ensuremath{\omega}}_{\mathrm{int}}=(\frac{p}{q}){\ensuremath{\omega}}_{\mathrm{ext}}$, with $p$ $q$ integers. These cannot be explained terms of familiar classical equation motion a single degree freedom, because inertial term is too small. observed behavior compared devil's staircase,...

Single crystals of ReB(2) have been prepared from an aluminum flux under inert gas flow. The are typically 1-3 mm in diameter and 500 microm thick, growing along the [002] direction with a distinct hexagonal morphology. Vickers microhardness nanoindentation testing indicate that (002) plane possesses highest hardness measured values 40.5 36.4 GPa, respectively. elastic anisotropy was examined indentation moduli basal (hk0) unknown indices 675 510 Four-probe electrical resistivity...

Specific-heat and dc magnetic-susceptibility measurements have been performed on $R{\mathrm{Ba}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{x}$ ($R$ denotes rare earth) compounds. These show that the rare-earth atoms behave as local moments above superconducting transition temperature of these compounds which can be high or higher than in nonmagnetic $\mathrm{Y}{\mathrm{Ba}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{x}$. Further, we find coexistence superconductivity magnetism...

As a point of entry to investigate the potential halogen-bonding interactions in construction functional materials and crystalline molecular machines, samples 1,4-bis(iodoethynyl)bicyclo[2.2.2]octane (BIBCO) were synthesized crystallized. Knowing that are common between electron-rich acetylenic carbons electron-deficient iodines, it was expected BIBCO rotors would be an ideal platform formation array rotors. Variable temperature single crystal X-ray crystallography established presence...

The magnetic phases of the ideal spin-1/2 triangular-lattice antiferromagnet Ba$_3$CoSb$_2$O$_9$ are identified and studied using $^{135,137}$Ba nuclear resonance (NMR) spectroscopy in fields ranging to 30T, oriented parallel near perpendicular crystallographic $ab$-plane. For both directions, saturation field is approximately 33T. Notably, NMR spectra provide microscopic evidence for stabilization an up-up-down spin configuration in-plane fields, giving rise one-third magnetization plateau...

Based on rotational dynamics measurements carried out with isomorphic co-crystals formed by halogen-bonding (XB) between tritylacetylene halides (TrX) and diazabicyclo[2.2.2]octane (dabco), we were able to distinguish the sources of enthalpic entropic components in free energy barrier. We describe formation 1:1 (TrX···N(R)3N) obtained from 1 equiv dabco either TrI or TrBr, respectively, give 4a 4b instead potential 2:1 complexes. The prepared solvent evaporation mechanochemical synthesis. No...

Quasi-two-dimensional superconductors with a sufficiently weak interlayer coupling allow magnetic flux to penetrate in the form of Josephson vortices for in-plane applied fields. A consequence is dominance Zeeman interaction over orbital effects. In clean limit, normal state favored superconductivity fields greater than paramagnetic limiting field, unless an intermediate, inhomogeneous stabilized. Presented here are nuclear resonance (NMR) studies Fulde-Ferrell-Larkin-Ovchinnikov (FFLO)...

$(\mathrm{TMTTF}{)}_{2}{\mathrm{AsF}}_{6}$ undergoes two phase transitions upon cooling from 300 K. At ${T}_{\mathrm{CO}}=103 \mathrm{K}$ a charge ordering (CO) occurs, and at ${T}_{\mathrm{SP}}(B=9 \mathrm{T})=11 the material spin-Peierls transition. Within intermediate, CO phase, disproportionation ratio is found to be least 3:1 ${}^{13}\mathrm{C}$ NMR ${T}_{1}^{\ensuremath{-}1}$ measurements on spin-labeled samples. Above ${T}_{\mathrm{SP}}$ up about ${3T}_{\mathrm{SP}}$ independent of...

We measured all nine elastic constants of a nonsuperconducting single crystal ${\mathrm{La}}_{2}$${\mathrm{CuO}}_{4}$ at 310, 297, and 44 K using small-sample resonant ultrasound technique. Weak features in frequencies dependent on compressional moduli were observed near 29 K, broad minimum occurred 38 the superconducting transition temperature optimally doped ${\mathrm{La}}_{2}$${\mathrm{CuO}}_{4}$. The are also reflected specific heat.

$^{13}\mathrm{C}$ nuclear magnetic resonance measurements were performed on $\ensuremath{\kappa}\mathrm{\text{\ensuremath{-}}}(\mathrm{BEDT}\mathrm{\text{\ensuremath{-}}}\mathrm{TTF}{)}_{2}\mathrm{Cu}(\mathrm{NCS}{)}_{2}$, with the external field placed parallel to quasi-2D conducting layers. The absorption spectrum is used determine electronic spin polarization ${M}_{s}$ as a function of $H$ at temperature $T=0.35\text{ }\text{ }\mathrm{K}$. A discontinuity in derivative $d{M}_{s}/dH$ an...

(TMTTF)$_2$SbF$_6$ is known to undergo a charge ordering (CO) phase transition at $T_{CO}\approx156K$ and another an antiferromagnetic (AF) state $T_N\approx 8K$. Applied pressure $P$ causes decrease in both $T_{CO}$ $T_N$. When $P>0.5 GPa$, the CO largely supressed, there no remaining signature of AF order. Instead, ground singlet. In addition establishing expanded, general diagram for physics TMTTF salts, we establish role electron-lattice coupling determining how system evolves with pressure.

We report on measurements of the thermal conductivity ${\mathrm{\ensuremath{\kappa}}}_{\mathrm{T}}$ close to Peierls transition temperature ${\mathrm{T}}_{\mathrm{P}}$ in ${\mathrm{K}}_{0.3}$${\mathrm{MoO}}_{3}$ and (${\mathrm{TaSe}}_{4}$${)}_{2}$I. In both cases there is an enhancement that peaks at transition. Simultaneous specific heat suggest anomalous behavior a result mode occupation rather than changes electron- or phonon-scattering processes.

We present ${}^{77}\mathrm{Se}$ nuclear magnetic resonance (NMR) Knight shift $(K)$ studies in pressurized $(\mathrm{TMTSF}{)}_{2}{\mathrm{PF}}_{6}$ with a field aligned along the b axis, perpendicular to conducting chains but parallel plane. On cooling deep into superconducting state, no observable change K from both spin echo and free induction decay signal was found. This strongly suggests triplet superconductivity $(\mathrm{TMTSF}{)}_{2}{\mathrm{PF}}_{6}.$

We theoretically investigate the interplay between charge ordering and magnetic states in quasi-one-dimensional molecular conductors TMTTF$_2X$, motivated by observation of a complex variation competing and/or coexisting phases. show that ferroelectric-type order increases two-dimensional antiferromagnetic spin correlation, whereas one-dimensional regime two different spin-Peierls are stabilized. By using first-principles band calculations for estimation transfer integrals comparing our...