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To study the anisotropic Josephson-vortex dynamics in the d-wave superconductors, the interplane resistance has been measured on layered organic superconductors κ ‐ ( ET ) 2 Cu ( NCS ) 2 and β ‐ ( BDA ‐ TTP ) 2 SbF 6 under magnetic fields precisely parallel to the conducting planes. For κ ‐ ( ET ) 2 Cu ( NCS ) 2 , in-plane angular dependence of the Josephson-vortex flow resistance is mainly described by the fourfold symmetry and dip structures appear when the magnetic field is applied parallel to the b- and c-axes. The obtained results have a relation to the d-wave superconducting gap symmetry. However, the absence of in-plane fourfold anisotropy was found for β ‐ ( BDA ‐ TTP ) 2 SbF 6 . The different anisotropic behavior is discussed in terms of the interlayer coupling strength.

The heat capacities of crystalline and liquid p-bromochlorobenzene were measured by adiabatic calorimetry between 6 and 350 K. The crystal melts at 337.99 K with an enthalpy and an entropy of fusion of 18390 J mol-1 and 55.41 J K-1 mol-1, respectively. Neither an ordering phase transition nor a glass transition was detected in the solid state, contrary to an expectation based on the apparent symmetry of the molecule at room temperature due to an orientational disorder. The calorimetric entropy of the gas was estimated using the vapor-pressure data. A comparison with spectroscopic entropy based on a quantum chemical calculation shows that the PBCB crystal has a residual entropy of about Rln 2 (R: gas constant), which is compatible with the orientational disorder at room temperature. The absence of a sizeable anomaly due to a glass transition suggests two possibilities: an undetectably small thermal anomaly around the glass transition, or a glass-transition temperature higher than the temperature of fusion.

Novel CT complexes derived from 4-alkylamino-TEMPO radical and 2,4,6,8-tetracyanoazulene have been prepared. Curie-Weiss behavior has been observed in the magnetic susceptibility of each complex with antiferromagnetic spin-spin interactions in the low temperature region on one hand and rather high conductivity has been found in the electrical conductivity of each complex with semiconducting behavior on the other hand.

A couple of spin systems with photo-responsive property have been developed, i. e., norbor-nadiene and spiropyran derivatives carrying TEMPO-substituent and their light-induced structural changes to the corresponding quadricyclane or merocyanine derivatives have been investigated together with the changes of their properties in solution as well as in the solid state.

The heat capacity of the title compound has been measured below room temperature by adiabatic calorimetry. A structural phase transition and a glass transition, both probably related to the intramolecular crankshaft motion, were detected at 273 K and 250 K, respectively. The degree of charge transfer (CT) was determined from IR spectroscopy as approximately 0.2e−. Since the central CC moiety of the stilbene molecule has a significant density in the HOMO, the observation of the phase and glass transitions means that the part involved in the CT interaction reorients itself in the crystal lattice above the glass transition temperature.

The crystal of \ensuremath{\lambda}-${(\mathrm{BETS})}_{2}{(\mathrm{F}\mathrm{e}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}{)\mathrm{C}\mathrm{l}}_{4}$ with $x\ensuremath{\approx}0.45$ undergoes successive superconducting and superconductor-to-insulator transitions around liquid helium temperature. The large diamagnetic susceptibility (\ensuremath{\approx}-35 emu/mol at 4 K) observed in the superconducting phase of the system with $x\ensuremath{\approx}0.47,$ which exhibits a superconducting transition at 4.3 K and superconductor-to-insulator transition at 3.7 K, can be regarded as evidence for the bulk nature of the superconductor-to-insulator transition. The anisotropy of the susceptibility and spin-flop behavior indicate that the system takes a \ensuremath{\pi}-d coupled antiferromagnetic insulating ground state, which is essentially the same as that of \ensuremath{\lambda}-${(\mathrm{BETS})}_{2}{\mathrm{FeCl}}_{4}$ exhibiting a coupled metal-insulator and antiferromagnetic transition at 8.5 K. The easy axis is parallel to the c direction. Unlike the Ga-rich system $(xl0.35)$ with superconducting ground state, the Fe-rich system such as \ensuremath{\lambda}-${(\mathrm{BETS})}_{2}{(\mathrm{F}\mathrm{e}}_{0.7}{\mathrm{Ga}}_{0.3}{)\mathrm{C}\mathrm{l}}_{4}$ shows a metal-insulator transition at ambient pressure. At high pressure, however, the \ensuremath{\pi} and d electrons tend to be independent of each other and the system takes a superconducting ground state.

Several photo-responsive norbornadiene as well as spiropyran derivatives with TEMPO radical substituents were prepared and their light-induced structural changes to the corresponding quadricyclanes or merocyanine dyes and reverse reactions to the starting materials were investigated. While the intermolecular magnetic interactions tend to be preserved in norbornadiene–quadricyclane systems in spite of the differences of their Weiss temperatures, a switching of the intermolecular magnetic interactions was observed in the spiropyran–merocyanine systems.

Temperature–pressure phase diagram of the 2-D organic conductor, κ-(DHDA-TTP)2SbF6 (DHDA-TTP = 2-(1,3-dithiolan-2-ylidene)-5-(1,3-dithian-2-ylidene)-1,3,4,6-tetrathiapentalene) is presented. This phase diagram exhibits a pressure boundary between insulator and Fermi liquid (FL). This boundary is considered as a critical pressure of quantum fluctuation between probable charge ordering and FL ground states. In the vicinity of the specific pressure, divergence of the prefactor A in ρ = ρ0 + AT2, is observed, where ρ is the in-plane resistivity and T is the temperature. Following the similar phase diagram to κ-(MeDH-TTP)2AsF6 by Yasuzuka et al., this is the second example in the two-dimensional 1/4-filled organic conductors, showing the temperature–pressure phase diagram of quantum critical behavior. It is remarkable that this kind of divergence of A at certain critical point is rather general phenomena at least in these 1/4-filled 2-D organic conductors, in contrast to the other 1/2-filled κ-type organic conductors, which show Kanoda's phase diagram with Mott insulator and superconductor.

A glass transition due to the freezing of intramolecular motion is reported for κ-(ET) 2 Cu[N(CN) 2 ]Br around 105 K on the basis of heat capacity spectroscopy utilizing chopped-light a.c. calorimetry on a single crystal around 10 Hz. The glass transition temperature in the daily time scale (ca. 10 3 s), well corresponds to the temperature below which the physical properties including the superconducting transition temperature depends on the thermal history (e.g. cooling rate or annealing). The history dependence is reasonably resolved by taking into account the glass transition.

Temperature dependence of the heat capacities of two organic conductors, (DMET) 2 BF 4 and (DMET) 2 ClO 4 , was measured by chopped-light ac calorimetry between 10 and 300 K. A “Mott-like” nature o...

λ-(BETS)2GaBrxCl4-x [BETS = bis(ethylenedithio)tetraselenafulvalene; 0 ≤ x ≤ 2] is a molecular superconductor with strongly correlated conduction electrons. The electrical transport properties of λ-(BETS)2GaBrxCl4-x are drastically changed by varying the bromine content x or by applying pressure. At ambient pressure, the superconducting transition could be observed for x < 0.75. The pressure and x dependencies of Tc were examined. The M−H curve (M = magnetization; H = magnetic field) at 2 K indicated the almost perfect Meissner state of the superconducting phase of λ-(BETS)2GaCl4. The Hc1 is ∼8 Oe for H⊥ and 12 Oe for H∥, where H⊥ and H∥ are the magnetic fields perpendicular and parallel to the c axis, respectively. The magnetic susceptibility of λ-(BETS)2GaBrxCl4-x increases with decreasing temperature to ∼60 K, below which the susceptibility becomes x-dependent and tends to be suppressed with increasing x. The isotropic decrease of the static susceptibility at lower temperature observed in the insulatin...

SQUID magnetometry and transport measurements combined with crystal structure refinement have been used to examine the variation in superconducting properties (Tc and Meissner fraction) in the molecular superconductor β″-(BEDT-TTF)4[(H3O)Fe(C2O4)3]·C6H5CN on replacing the C6H5CN guest molecule with pyridine (C5H5N). Up to approximately 65% pyridine substitution there is only a small decrease in Tc and Meissner fraction but above that the superconductivity is suppressed.

The electric and magnetic properties of a series of highly correlated two-dimensional organic \ensuremath{\pi} conductors incorporating magnetic ions (${\mathrm{Fe}}^{3+}$ with $S=\frac{5}{2}$), $\ensuremath{\lambda}\ensuremath{-}{\mathrm{BETS}}_{2}{\mathrm{FeBr}}_{x}{\mathrm{Cl}}_{4\ensuremath{-}x}$ [$\mathrm{B}\mathrm{E}\mathrm{T}\mathrm{S}=\mathrm{b}\mathrm{i}\mathrm{s}(\mathrm{ethylenedithio})\mathrm{tetraselenafulvalene},$ $x=0--0.8$] were examined by controlling the Br content (x). A broad resistivity maximum at 100 $(x\ensuremath{\approx}0)--50\mathrm{K}$ $(x\ensuremath{\approx}0.7)$ indicating the strong correlation of \ensuremath{\pi} conduction electrons becomes prominent with increasing x. At the same time the metal-insulator (MI) transition temperature ${(T}_{\mathrm{MI}})$ increases from 8.5 $(x=0)$ to 18 K $(x=0.7).$ The crystal with $x=0.8$ shows a semiconductor-insulator transition around 20 K. At $0lxl0.2,$ the MI transition and the antiferromagnetic (AF) transitions take place cooperatively around 8.5 K ${(T}_{N}\ensuremath{\approx}{T}_{\mathrm{MI}}).$ A large magnetization drop was observed at ${T}_{\mathrm{MI}}$ for the magnetic field parallel to the c axis $(H\ensuremath{\parallel}c),$ which indicates the appearance of localized \ensuremath{\pi} spins $(S=\frac{1}{2})$ and a strong AF coupling of \ensuremath{\pi} and d spin systems. For $0.3lxl0.5,$ two anomalies were observed in the magnetization-temperature $(M\ensuremath{-}T)$ curve. The high-temperature anomaly corresponds to a MI transition ${(T}_{\mathrm{MI}})$ and the low-temperature one corresponds to an AF ordering of the ${\mathrm{Fe}}^{3+}$ spins ${(T}_{N}).$ In this case, the relatively small magnetization drop observed at ${T}_{\mathrm{MI}}$ suggests a small coupling of \ensuremath{\pi} and d spin systems. For $xg0.6,$ the magnetization drop at ${T}_{\mathrm{MI}}$ disappeared, which shows that the \ensuremath{\pi} and d electron systems are decoupled and the \ensuremath{\pi} electron system undergoes MI transition independently of the d spin systems. The disappearance of the susceptibility anomaly at ${T}_{\mathrm{MI}}$ indicates that the \ensuremath{\pi} electron system transforms to a nonmagnetic insulating state below ${T}_{\mathrm{MI}}.$ On the other hand, the anisotropy of M showing the development of a AF spin structure of the Fe spins was observed independently of $x(0lxl0.8).$ Around $x=0.3\ensuremath{-}0.5,$ the direction of the easy axis of the AF spin structure changes from parallel to the c axis $(xl0.2)$ to perpendicular to it $(xg0.6).$ In other words, the direction of easy axis is varied according to the magnitude of $\ensuremath{\pi}\ensuremath{-}d$ coupling. Magnetoresistance measurements showed that ${T}_{\mathrm{MI}}$ of $\ensuremath{\lambda}\ensuremath{-}{\mathrm{BETS}}_{2}{\mathrm{FeBr}}_{0.7}{\mathrm{Cl}}_{3.3}$ is almost independent of the magnetic field below 1 kbar. But a field-restored highly conducting state similar to that of $\ensuremath{\lambda}\ensuremath{-}{\mathrm{BETS}}_{2}{\mathrm{FeCl}}_{4}$ was observed at high pressure. The Weiss temperature (\ensuremath{\theta}) estimated from the $M\ensuremath{-}T$ curve at ${T}_{\mathrm{MI}}lTl30\mathrm{K}$ decreases with increasing x.

The physical properties of a series of organic superconductors with fourfold quasistacking structures, $\ensuremath{\lambda}\ensuremath{-}{\mathrm{BETS}}_{2}\mathrm{Ga}{X}_{z}{Y}_{4\ensuremath{-}z}$ [BETS=bis(ethylenedithiotetraselenafulvalene; $X,Y=\mathrm{F},$ Cl, Br; $0lzl2)]$ are changed continuously by tuning the value of $z.$ The compound $\ensuremath{\lambda}\ensuremath{-}{\mathrm{BETS}}_{2}{\mathrm{GaBr}}_{z}{\mathrm{Cl}}_{4\ensuremath{-}z},$ has a superconducting ground state for $0lzl{z}_{c}$ (\ensuremath{\approx}0.8) and a semiconducting state for ${z}_{c}lzl2.0.$ The maximum ${T}_{c}$ is about 10 K, showing the existence of a 10-K class of non-ET organic superconductors [ET=bis(ethylenedithio)tetrathiafulvalene]. The temperature dependence of the resistivity closely resembles that for \ensuremath{\kappa}-type ET superconductors but the susceptibility behavior is different. The susceptibility of $\ensuremath{\lambda}\ensuremath{-}{\mathrm{BETS}}_{2}{\mathrm{GaBr}}_{1.5}{\mathrm{Cl}}_{2.5}$ is isotropic and decreases fairly sharply below 30 K. No indication of a spin-flop transition was observed at 10 K, suggesting that the insulating phase that neighbors the superconducting phase is not antiferromagnetic at least down to 10 K.

Several organic radical compounds based on TEMPO radical with cholesterol and benzylideneamine cores ( 3a – c ) were prepared. The radical compounds were found to freeze into glassy state when cooled from their isotropic liquid state and characteristic heat-responsive magnetic properties were observed in the radicals due to the phase transitions.

The syntheses of a range of enantiopure organosulfur donors with hydrogen bonding groups are described including TTF related materials with two, four, six and eight hydroxyl groups and multiple stereogenic centres and a pair of chiral N-substituted BEDT-TTF acetamides. Three charge transfer salts of enantiopure poly-hydroxy-substituted donors are reported, including a 4:1 salt with the meso stereoisomer of the dinuclear [Fe2(oxalate)5]4− anion in which both cation and anion have chiral components linked together by hydrogen bonding, and a semiconducting salt with triiodide.

A novel molecular complex of tetramethyltetrathiafulvalene (TMTTF) was prepared by the treatment with TiF4. The X-ray analysis reveals the exsistence of a trimer of TMTTF’s and a Ti2F102− anion in a triclinic unit cell of the dimension; a = 10.934(3), b = 12.798(2), c = 8.000(1) A, α = 103.86(1), β = 107.08(2), γ = 75.02(2)°. All the molecular planes of TMTTF are nearly parallel. The trimers stack parallel to the a axis, and the intertrimer interaction is estimated to be weak. A semiconductive behavior with a relatively large Seebeck coefficient was observed (ρ = 3 × 102 Ω cm, Ea = 0.26 eV, and S = −0.41 mV K−1 along the a axis). Weak electron spin resonance (ESR) absorption was observed to be characteristic of low-dimensional diffusive spin systems.

The molecular structure of 9,10-diethyl-9,10-diphospha-9,10-dihydroanthracene (PEPP) was determined by X-ray analysis. The central six-membered ring takes a boat conformation with two phosphorus atoms being the stem and stern, and the condensed tricyclic skeleton forms a butterfly-like structure. Of the two ethyl groups, which are attached to two P atoms in the central ring, the one is placed toward outside the skeleton (extra), and the other is located toward the inside of the ‘butterfly’ (intra). The observed redox potential of 0.63 V vs. Ag/AgCl suggests that this molecule has a fairly good electron-donating characteristics. From the spectroscopic observation and a quantum-chemical calculation, the donating orbital is estimated to be that of lone pair electrons at the P atom that attaches to the intra ethyl group.

We applied magneto-optical techniques to investigate the electron spin resonance (ESR) spectra of single crystal and powder samples of the organic superconductor β-(BEDT- TTF) 4 [(H 3 O)Fe (C 2 O 4 ) 3 ]C 6 H 5 CN. Data were obtained in magnetic fields up to 10 Tesla using both cylindrical and rectangular resonators at 55, 63 and 72 GHz and transmission measurements at 95 and 190 GHz with field modulation. Analysis of the high field-high frequency ESR lines for different field orientations and temperatures allows the determination of the g-value anisotropy and the zero-field splitting parameters for the Fe 3+ ions (S = 5/2), showing that they occupy a site with distorted octahedral symmetry. The temperature and frequency dependences of the magneto-optical spectra are used to identify the nature of the interaction between localised Fe spins and between the local moments and the delocalised carriers.

We report magnetotransport measurements performed in magnetic fields of up to 33 T and at low temperatures (0.45 K

In order to discuss the stability of the gapless features in the spin liquid state against magnetic fields, we report results and analyses of low-temperature heat capacity measurements of EtMe3Sb[Pd(dmit)2]2 under magnetic fields. The large upturn of [Formula: see text] at 0 T observed previously in EtMe3Sb[Pd(dmit)2]2 can be attributed to the rotational tunneling of the methyl groups in the counter cations and this upturn is suppressed by applying magnetic fields. The phenomenological resemblance of the feature under magnetic field was confirmed by comparative discussion of heat capacity measurement of metal complex of [Cu(acac)(OCH[Formula: see text]]2 having similar methyl groups. The gapless character evidenced by the finite electronic heat capacity coefficient, [Formula: see text] was found to be retained upon applying 17 T in EtMe3Sb[Pd(dmit)2]2, which means that spin liquid ground state is stable against high magnetic fields. The finite [Formula: see text] in the spin liquid compounds is considered to be related to a kind of density of states in spin excitations rather than those determined by disorders such as spin glasses.

Low-temperature heat capacity of the organic superconductor λ-(BETS)2GaCl4 in a temperature range between 0.6 and 10 K was measured for a single crystal sample by relaxation calorimetry technique. The contribution of electronic heat capacity in the superconducting state shows T2 dependence at lower temperature that indicates the existence of quasi-particle excitations from the line-nodal gap structure of d-wave pairing. The recovery of the electronic heat capacity coefficient, γ by magnetic field shows H1/2 dependence that is consistent with the picture of line-nodal superconductor. In spite of the different packing from typical organic superconductors κ-(BEDT-TTF)2X, the λ-type BETS salt also shows a feature of d-wave symmetry pairing.

The title compound, C6H4S4+·C9H16NO5S−, which includes an organic diamagnetic anion, was obtained unexpectedly by metathesis of the tetra­phenyl­phospho­nium salt of an organic free-radical anion, 2,2,6,6-tetra­methyl­piperidinyl­oxy-4-hydroxy-4-sulfonate, with (TTF)3(BF4)2 (TTF = tetra­thia­fulvalene).

[reaction: see text] Naphthopyran derivatives with aminoxyl substituents (4a,b) gave the corresponding open-formed isomers (5a,b) by irradiation, which could be changed back to the starting closed-formed naphthopyrans by the treatment with SiO(2) as a catalyst. The tuning of intermolecular magnetic interactions between the isomer couples was found to be possible in these reversible systems.

The purely organic paramagnetic charge-transfer salt (TTF)3(PO-CON(CH3)C2H4SO3)2 was prepared. The anisotropic anion forms a head-to-head arrangement in the anionic layer, giving dual donor layers with different oxidation states. SQUID magnetometry indicates that spins are localized not only on the free radical (PO) but also on both TTF layers.

© The Japan Society for Analytical Chemistry.The title compound, (C24H20P)(FeN2O2Cl2), was prepared by adapting of literature methods. It crystallizes in the tetragonal space group P4. The structure consists of one P(C6H5)4 cation and one Fe(NO)2Cl2 anion. The anion has one ordered NO group and one ordered Cl ligand. The other two ligands are disordered, such that one half of NO and a half of Cl are located at each position.

A series of aminoxyl radicals (nitronyl nitroxide or TEMPO) bearing biphenylcarbonitrile as a mesogenic core ( 2a–2c and 3a–3c ) was prepared. Among them, unusual magnetic transition from the original Curie–Weiss phase to another magnetic phase well expressed by a singlet–triplet model was found in the 4′-undecyloxy-4-biphenylcarbonitrile derivative with oxocarbonyl-TEMPO through the thermal transition.

The title compound, Cs(3)[Cr(C(2)O(4))(3)].2H(2)O, has been synthesized for the first time and the spatial arrangement of the cations and anions is compared with those of the other members of the alkali metal series. The structure is built up of alternating layers of either the D or L enantiomers of [Cr(oxalate)(3)](3-). Of note is that the distribution of the [Cr(oxalate)(3)](3-) enantiomers in the Li(+), K(+) and Rb(+) tris(oxalato)chromates differs from those of the Na(+) and Cs(+) tris(oxalato)chromates, and also differs within the corresponding BEDT-TTF [bis(ethylenedithio)tetrathiafulvalene] conducting salts. The use of tris(oxalato)chromate anions in the crystal engineering of BEDT-TTF salts is discussed, wherein the salts can be paramagnetic superconductors, semiconductors or metallic proton conductors, depending on whether the counter-cation is NH(4)(+), H(3)O(+), Li(+), Na(+), K(+), Rb(+) or Cs(+). These materials can also be superconducting or semiconducting, depending on the spatial distribution of the D and L enantiomers of [Cr(oxalate)(3)](3-).

A couple of naphthalenediimide derivatives carrying TEMPO radicals were found to exhibit n-type FET with mobilities up to 2.6×10−5 cm2/V·s as the first examples of spin-carrying acceptor systems wh...

We have examined time-averaged charges of the molecular donors around the phase boundary between the insulating, superconducting, and metal phases for ${\ensuremath{\beta}}^{\ensuremath{''}}$-type ET [$\mathrm{ET}=\text{bis}$-ethelenedithio-tetrathiafulvalene] salts with one (two) hole(s) per two (three) molecules by using vibrational spectroscopy. Around the phase boundary, the site charges are neither those expected for a well-developed charge-ordered (CO) state nor a homogeneous distribution. The molecular charges exhibit an inhomogeneous distribution just above the insulator-superconductor transition temperature. We have analyzed the distribution of the site charges from the viewpoint of the alternation of intersite Coulomb interactions along the stacking direction. The closeness in the energy of several CO patterns mostly contributes to the inhomogeneous distribution, whereas a large difference (no difference) in the energy levels contributes to the CO (homogeneous) state. Our observations indicate that the instability due to the closeness in the energy of several distributions correlates with the insulator-superconductor transition in nondimerized or weakly dimerized molecular conductors.

Electron spin resonance reveals the spin behavior of conduction ($\ensuremath{\pi}$) and localized ($d$) electrons in $\ensuremath{\beta}\mathrm{\text{\ensuremath{-}}}(\mathrm{BDA}\mathrm{\text{\ensuremath{-}}}\mathrm{TTP}{)}_{2}M{\mathrm{Cl}}_{4}$ ($M=\mathrm{Fe}$, Ga). Both the ${\mathrm{Ga}}^{3+}(S=0)$ and ${\mathrm{Fe}}^{3+}(S=5/2)$ compounds exhibit a metal-insulator transition at 113 K with the simultaneous formation of a spin-singlet ground state in the $\ensuremath{\pi}$ electron system of the donor molecules. The behavior is consistent with charge ordering in $\ensuremath{\beta}\mathrm{\text{\ensuremath{-}}}(\mathrm{BDA}\mathrm{\text{\ensuremath{-}}}\mathrm{TTP}{)}_{2}M{\mathrm{Cl}}_{4}$ at the metal-insulator transition. At 5 K, the ${\mathrm{Fe}}^{3+}$ compound orders antiferromagnetically, even though the $\ensuremath{\pi}$ electrons, which normally would facilitate magnetic exchange, are localized nonmagnetic singlets.

A new bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF)-based salt with a ferrocenyl moiety, alpha' ''-(BEDT-TTF)(4)(Fe(C(5)H(4)SO(3))(2)).6H(2)O, has been prepared. The ferrocenyl part of this salt is neutral and diamagnetic, but the magnetic susceptibility is well modeled by a Curie-Weiss law with C = 0.142 emu.K.mol(-1) (approximately 1/3 of s = 1/2 spin). The spin is likely to be localized on the donor layer because of its unique charge disproportionation.

We report magnetotransport measurements on the quasi-two-dimensional charge-transfer salts β″-(BEDT-TTF)4[(H3O)M(C2O4)3]Y, with Y=C6H5NO2 and C6H5CN using magnetic fields of up to 45 T and temperatures down to 0.5 K. A surprisingly robust superconducting state with an in-plane upper critical field Bc2 33T, comparable to the highest critical field of any BEDT-TTF superconductor, and critical temperature Tcâ 7K is observed when M=Ga and Y=C6H5NO2. The presence of magnetic M ions reduces the in-plane upper critical field to 18T for M=Cr and Y=C6H5NO2 and M=Fe and Y=C6H5CN. Prominent Shubnikov-de Haas oscillations are observed at low temperatures and high magnetic fields, showing that the superconducting salts possess Fermi surfaces with one or two small quasi-two-dimensional pockets, their total area comprising 6% of the room-temperature Brillouin zone; the quasiparticle effective masses were found to be enhanced when the ion M was magnetic (Fe or Cr). The low effective masses and quasiparticle densities, and the systematic variation of the properties of the β″-(BEDT-TTF)4[(H3O)M(C2O4)3]Y salts with unit-cell volume points to the possibility of a superconducting groundstate with a charge-fluctuation-mediated superconductivity mechanism such as that proposed by Merino and McKenzie [Phys. Rev. Lett. 87, 237002 (2001)], rather than the spin-fluctuation mechanism appropriate for the κ-(BEDT-TTF)2X salts. © 2005 The American Physical Society.

The synthesis of DHOT-TTP, in which one sulfur atom of BDH-TTP [2,5-bis(1,3-dithiolan-2-ylidene)-1,3,4,6-tetrathiapentalene] is substituted by oxygen, has been accomplished. The DHOT-TTP donor possesses a less planar molecular structure than BDH-TTP, and gives a metallic AuI 2 salt stable down to 1.4 K, the crystal structure of which is elucidated.

The title compound, (CHP)(CHNOS)CuI.0.34HO, was obtained by the slow evaporation of a solvent from an acetonitrile solution containing a mixture of (PPh)N,N'-disulfobenzoquinonediimine and CuI. The structure consists of a one-dimensional metal-organic framework of the dianion and CuI. The anionic chains are surrounded by relatively large counter-cations, and are thus well isolated from each other.

A trans-azobenzene derivative with a long alkyl chain and a TEMPO radical showed photo-induced isomerization to become the corresponding cis-isomer with a significant change of its intermolecular magnetic interaction from a weak ferromagnetic one based on the CW model to a relatively strong antiferromagnetic one based on the ST model with the J-value of 36.7 K.

We have investigated pressure- and magnetic-field-dependent electrical transport properties in the charge transfer salts $\ensuremath{\beta}\text{\ensuremath{-}}{(\mathrm{BDA}\text{\ensuremath{-}}\mathrm{TTP})}_{2}M{\mathrm{Cl}}_{4}\phantom{\rule{0.3em}{0ex}}(M=\mathrm{Fe},\mathrm{Ga})$, both of which show a metal-insulator (MI) transition around $120\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ at ambient pressure. The zero field temperature-pressure phase diagrams of the two compounds are quite similar; the MI transition temperature decreases with pressure, and superconductivity is observed in both the magnetic and non-magnetic compounds above $\ensuremath{\sim}4.5\phantom{\rule{0.3em}{0ex}}\mathrm{kbar}$. Likewise, Shubnikov-de Haas effect measurements show nearly identical Fermi surfaces. These similarities suggest that the magnetic interaction $J$ between the conduction electrons and the magnetic moments in $\ensuremath{\beta}\text{\ensuremath{-}}{(\mathrm{BDA}\text{\ensuremath{-}}\mathrm{TTP})}_{2}{\mathrm{FeCl}}_{4}$ is small. Nevertheless, magnetoresistance measurements show remarkable differences and reveal that magnetic interactions with the conduction electrons are still effective in $M=\mathrm{Fe}$ compounds.

We report high-field magnetotransport measurements on ${\ensuremath{\beta}}^{\ensuremath{''}}\ensuremath{-}(\mathrm{BEDT}\ensuremath{-}\mathrm{TTF}{)}_{4}[({\mathrm{H}}_{3}\mathrm{O})M({\mathrm{C}}_{2}{\mathrm{O}}_{4}{)}_{3}]Y,$ where $M=\mathrm{Ga},$ Cr, and Fe and $Y={\mathrm{C}}_{5}{\mathrm{H}}_{5}\mathrm{N}.$ We observe similar Shubnikov--de Haas oscillations in all compounds, attributable to four quasi-two-dimensional Fermi-surface pockets, the largest of which corresponds to a cross-sectional area $\ensuremath{\approx}8.5%$ of the Brillouin zone. The cross-sectional areas of the pockets are in agreement with the expectations for a compensated semimetal, and the corresponding effective masses are $\ensuremath{\sim}{m}_{\mathrm{e}},$ rather small compared to those of other BEDT-TTF salts. Apart from the case of the smallest Fermi-surface pocket, varying the M ion seems to have little effect on the overall Fermi-surface topology or on the effective masses. Despite the fact that all samples show quantum oscillations at low temperatures, indicative of Fermi liquid behavior, the sample and temperature dependence of the interlayer resistivity suggest that these systems are intrinsically inhomogeneous. It is thought that intrinsic tendency to disorder in the anions and/or the ethylene groups of the BEDT-TTF molecules leads to the coexistence of insulating and metallic states at low temperatures. A notional phase diagram is given for the general family of ${\ensuremath{\beta}}^{\ensuremath{''}}\ensuremath{-}(\mathrm{BEDT}\ensuremath{-}\mathrm{TTF}{)}_{4}[({\mathrm{H}}_{3}\mathrm{O})M({\mathrm{C}}_{2}{\mathrm{O}}_{4}{)}_{3}]Y$ salts.

The preparation, crystal structure and physical properties of β-(BDA-TTP)2GaCl4 has been investigated; the salt exhibits superconductivity at 3.1 K (onset) under a hydrostatic pressure of 7.6 kbar.

The title compound, C(24)H(20)P(+).C(9)H(17)NO(5)S(-), consists of an organic monovalent cation and an organic monovalent anion, the latter being derived from the TEMPO radical (TEMPO is 2,2,6,6-tetramethylpiperidin-1-oxyl). Two inversion-related anions interact via two -O-H.O-S- hydrogen bonds, forming a dimer in which there are no short contacts between the spin centres (-N-O) of the TEMPO(OH)SO(3)(-) anions. Furthermore, no significant magnetic interaction is observed between the dimers because the dimer is surrounded by cations. These results are consistent with the paramagnetic behaviour of the title salt.

Systematic measurements of the magnetic torque of organic π–d conductors κ-(BDH-TTP)2FeX4 (X = Br, Cl) have been performed to investigate the magnetic properties. The Fe 3d spins of both salts show antiferromagnetic (AF) orders at low temperatures. A simple two-sublattice model is found to well reproduce the essential features of the torque data in the AF states. The exchange interaction and anisotropic parameter of the ligand field obtained by the simulations are consistent with previous experimental results.

A couple of naphthalenediimide derivatives carrying TEMPO radicals were found to exhibit n-type FET with mobilities up to 2.6×10−5 cm2/V·s as the first examples of spin-carrying acceptor systems wh...

A novel bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF)-based salt with an aminoxyl radical 2,2,5,5-tetramethyl-3-pyrrolin-1-oxyl (PO) has been prepared. The salt has α-type 2-D conducting sheets and is a semiconductor with ρ = 26 Ω·cm and E = 0.31 eV. The temperature dependence of the magnetic susceptibility suggests that both the aminoxyl radical and the BEDT-TTF layer have local spin moments at room temperature. Copyright © 2008 The Chemical Society of Japan.

Four kinds of TEMPO-substituted 1,4-benzoquinone derivatives were found to afford single-component CT crystals formed by the interactions between a benzoquinone ring and one or two TEMPO groups of ...

The reactions of TEMPO derivatives having a benzylideneamine unit with Cu(hfac)2 revealed unexpected formation of a complex consisting of 4-amino-TEMPO and Cu(hfac)2 and its crystal structure and magnetic properties showed marked difference from those of the corresponding Mn(hfac)2 complex and a complex derived from bis-TEMPO-substituted-ethylenediamine