Fermiology and thermodynamic properties of κ-(ET)2I3

Wosnitza, J.; Herrmann, Nico; Liu, X.; Schweitzer, Dieter

doi:10.1016/0379-6779(94)02667-n

Cited by 8 publications

(8 citation statements)

References 6 publications

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“…Our results compare well with EHT and LDA calculations. The topology of the calculated FS agrees with available SdH data on κ-phase ET salts [10], [15], [23]. We observe that these experiments strongly support a Fermi-liquid picture for OSC.…”

supporting

confidence: 84%

“…LDA bands for κ-ET 2 Cu(NCS) 2 and ET-Br [14] are also similar, apart from an overall bandwidth narrowing. Moreover the FS topology agrees with the available experimental Shubnikov-de Haas (SdH) data on κ-ET 2 Cu(NCS) 2 [10] and on κ-ET 2 I 3 [15]. Therefore the dimer model offers a manifestly good description of the κ-phase band structure.…”

supporting

confidence: 83%

“…On the other hand, residual many-body effects are important in determining the electronic properties of OSC. The effective masses inferred from SdH data via the Lifshits-Kosevich formula for κ-ET 2 Cu(NCS) 2 [10], κ-ET 2 I 3 [15], and ET-Br [23] are about two times larger than our calculated effective masses. Moreover, the calculated normal-state electronic specific heat is quasi-linear with T , but its slope, γ ≈ 7.5 mJ/mole • K 2 , is 2-3 times smaller than the experimental values for ET-Br, κ-(ET) 2 Cu(NCS) 2 , and κ-ET 2 I 3 [19].…”

mentioning

confidence: 70%

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The dimer model for κ-phase organic superconductors

Visentini¹,

Painelli²,

Girlando³

et al. 1998

Europhys. Lett.

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We prove that the upper electronic bands of κ-phase BEDT-TTF salts are adequately modeled by an half-filled tight-binding lattice with one site per cell. The band parameters are derived from recent ab initio calculations, getting a very simple but extremely accurate one-electron picture. This picture allows us to solve the BCS gap equation adopting a real-space pairing potential. Comparison of the calculated superconducting properties with the experimental data points to isotropic s0-pairing. Residual many-body or phonon-mediated interactions offer a plausible explanation of the large variety of physical properties observed in κ-phase BEDT-TTF salts.PACS numbers: 71.15.Fv, 74.20.Fg, 74.70.Kn, Superconductivity (SC) in organic charge transfer (CT) salts has been discovered more than 15 years ago. At present, κ-phase BEDT-TTF (ET) salts are the most promising organic superconductors (OSC) [1]. OSC have similar features to cuprate superconductors: they exhibit highly bidimensional structures, narrow electronic bands, low carrier densities and possibly strong electronic correlations. Superconducting properties are also similar in organics and cuprates, exhibiting singlet pairing [2], very low coherence lengths, high magnetic penetration depths and critical fields [1]. Perhaps the most characteristic feature of cuprate superconductors is the competition between SC and antiferromagnetism (AFM). This competition shows up also in OSC, as demonstrated by the presence of antiferromagnetic spin fluctuations in the metallic state of several compounds [2], or even by reentrant SC in the presence of magnetic order. In this respect the different behavior of κ-ET 2 Cu[N(CN) 2 ]X (ET-X) salts where X=Cl, Br is noteworthy: the two compounds are isostructural, but at ambient pressure the Br-compound is a superconductor with T c = 11.6 K, whereas the Clcompound is a Mott insulator with (possibly commensurate) antiferromagnetic ordering [2]. On the other hand, even a very small external pressure (270 bar), turns ETCl to the superconducting ground state (T c = 12.8 K) [1]. Experimental studies of normal and superconducting state properties in OSC are still scanty and often inconclusive, due to the extreme sensitivity of the material to pressure, radiation and sample preparation. At the same time, the amount of theoretical work on OSC is scarce if compared with that developed for cuprates, possibly due to the apparent complexity of the OSC structures. In the following we will show that, by a proper choice of the basis functions, the electronic structure of κ-phase ET salts can be accurately described in terms of a rectangular lattice with nearest and next-nearest neighbor interactions. Similar one-band models are often adopted in the study 1

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supporting

confidence: 84%

supporting

confidence: 83%

mentioning

confidence: 70%

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The dimer model for κ-phase organic superconductors

Visentini¹,

Painelli²,

Girlando³

et al. 1998

Europhys. Lett.

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“…In the case of κ-(BEDT-TTF) 2 Cu[N(CN) 2 ]Br salt, Andraka et al also performed heat capacity measurements by relaxation calorimetry under magnetic field up to 14 T and obtained γ = (22 ± 3) mJ K –2 mol –1 and Debye temperature of 210 K. They also estimated Δ C p / γT c = 2 ± 0.5, which is comparable with the data of κ-(BEDT-TTF) 2 Cu(NCS) 2 . Thermodynamic data of other superconductive salts are listed in Table for κ-(BEDT-TTF) 2 I 3 , , κ-(BEDT-TTF) 2 Ag(CN) 2 H 2 O, and κ L -(BEDT-TTF) 2 Ag(CF 3 ) 4 TCE, where TCE is 1,1,2-trichloroethane, and κ-(BEDT-TTF) 4 Hg 2.89 Br 8 . − …”

Section: Organic Conductorsmentioning

confidence: 99%

Update 1 of: Calorimetric Investigation of Phase Transitions Occurring in Molecule-Based Magnets

et al. 2013

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“…In this family the highest superconducting transition temperature in organic materials is found with T, KZ 12. 8 K in x-(ET)2Cu[N(CN)z]Cl at 0.3 x 10' P a [l].…”

Section: Introductionmentioning

confidence: 99%

Effect of high hydrostatic pressure on the magnetoresistance quantum oscillations of the quasi‐two‐dimensional organic superconductor x‐(BEDT‐TTF)₂i₃

Helm

Kraak

Schweitzer

1996

Physica Status Solidi (b)

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High-field niagnetotransport investigations of single crystals of the quasi-two-dimensional organic compound x-(BEDT-TTF)gI:( under hydrostatic pressure up to 9 x lo8 Pa are presented. Pronounced Shubnikov-de Haas oscillations are observed in magnetic fields up to 12 T over the whole pressure range. These quantum oscillations are affected remarkably by hydrostatic pressure. All of the four funtlaniental fields detected rise with increasing pressure corresponding to an enhancement of the extremal areas of the Fermi surface in x-(BEDT-TTF)213. The experimentally determined cyclotron effective masses of the charge carriers decrcase with increasing pressure. The FFT amplitudes of the Shubnikov-dc Haas oscillations show a very complex pressure dependence reflecting a more complicated structure of the electron system than the relatively simple topology of the calculated Fcrmi surface involves. The pressure-induced changes of the Fermi surface are discussed in the framework of an effective dinier model and conipared with equivalent investigations on the isostriictiiral cornpourid x-(ET)zCu(NCS)z.Es werden Magnetotransport-Uritersuchungen an Einkristallen der quasi-zweidimensionalen organischen Verbindung x-(BEDT-TTF)zI:$ unter hydrostatischem Druck bis 9 x 10' P a vorgestellt. Im gesamten Druckbereich sind in Magnetfeldern bis 12 T ausgepragte Shubnikov-de Haas-Oszillationen z i i beobachten. Diese Quantenoszillationen anderri sich deutlich unter dem EinfluB von hohern hydrostatischen Druck. Alle vier nachgewiesenen Fundamentalfelder nehmen bei Druckerholiung zu, verbunden mit ciner Vergroflerung der Extremalquerschnitte der Fernii-Oberflache in X-(BEDT-TTF)z13, Die experirneritell bestimmten effektiven Zyklotronrnassen der Ladungstrager sinken unter Druckzunahme. Die FFT-Amplituden der Shubnikov-de Haas-Oszillation zeigen eine sehr komplexe Druckabhangigkeit, die auf eine kompliziertere Elektronenstruktur, als sich aus der relativ einfachen Topologie der berechneten Fermi-Oberflache ergibt, schlieJ3en 1aBt. Die druckinduzierten Veranderungen der Fermi-Oberflache werden im Rahmen eines effektiven Dimer-Modells diskutiert mid rnit aquivalentcn Untersuchungen an der isostrukturellen Verbindung x -( E T )~C~( N C S )~ verglichen.

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Fermiology and thermodynamic properties of κ-(ET)2I3

Cited by 8 publications

References 6 publications

The dimer model for κ-phase organic superconductors

The dimer model for κ-phase organic superconductors

Update 1 of: Calorimetric Investigation of Phase Transitions Occurring in Molecule-Based Magnets

Effect of high hydrostatic pressure on the magnetoresistance quantum oscillations of the quasi‐two‐dimensional organic superconductor x‐(BEDT‐TTF)₂i₃

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Fermiology and thermodynamic properties of κ-(ET)2I3

Cited by 8 publications

References 6 publications

The dimer model for κ-phase organic superconductors

The dimer model for κ-phase organic superconductors

Update 1 of: Calorimetric Investigation of Phase Transitions Occurring in Molecule-Based Magnets

Effect of high hydrostatic pressure on the magnetoresistance quantum oscillations of the quasi‐two‐dimensional organic superconductor x‐(BEDT‐TTF)2i3

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Product

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Effect of high hydrostatic pressure on the magnetoresistance quantum oscillations of the quasi‐two‐dimensional organic superconductor x‐(BEDT‐TTF)₂i₃