Crystal structures and properties of some cation radi EDOMDTTTF, EDOVDTTTF, EDOBTTF, EDOPDSDTF, EDODMPTTF, BEDTTTF and BMDTTTF

Terzis, Aris; Hountas, A.; Hilti, B.; Mayer, G. J.; Zambounis, J. S.; Lagouvardos, D. J.; Kakoussis, V. C.; Mousdis, George A.; Papavassiliou, George C.

doi:10.1016/0379-6779(91)91938-7

Cited by 19 publications

(9 citation statements)

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“…The band structure of a single layer of the t phase, calculated with the extended HuÈ ckel method, contains a¯at-bottomed band (Terzis et al 1991).…”

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confidence: 99%

Transport around criticalities: Localization-delocalization and paramagnetic-ferromagnetic transitions

Aoki

2001

Philosophical Magazine B

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We study two examples of transport properties of electron systems in the vicinity of a critical point. The ®rst example, a one-body problem, is the disorder-driven metal±insulator transition in the integer quantum Hall system. We have numerically examined the multifractality of the critical wavefunction, which is relevant to an anomalous diOE usion of electrons. The second example, a many-body problem, is the paramagnetic±ferromagnetic transition in a strongly correlated clean electron system. We show that the proximity to ferromagnetism can give rise to a negative magnetoresistance. These exemplify how a criticality manifests itself in transport properties.} 1. Introduction Central to the understanding of electron systems are critical phenomena which occur in various manners, in both one-body problems and many-body problems. It is then an intriguing question to ask how electronic transport properties can re¯ect the criticality when the system is at or around a critical point.In the one-body picture an example is the localization±delocalization transition in disordered systems. We can start by asking ourselves whether this transition may be regarded as a phase transition. The present author (Aoki 1983(Aoki , 1986 suggested that wavefunctions at the Anderson transition should be self-similar (fractal) just as the critical point in a phase transition is characterized by a diverging correlation length with scale-invariant¯uctuations. To be more precise, the self-similarity in critical wavefunctions extends beyond a single scale transformation , so the idea has been subsequently developed into the multifractal analysis (Castellani and Peliti 1986, Schreiber and Grassback 1991, Avishai et al. 1995.The criticality of the wavefunction proposed in general has been analysed for the quantum Hall system in particular (Aoki 1983(Aoki , 1986. In discussing the integer quantum Hall eOE ect, Aoki and Ando (1981) have pointed out, ®rstly, that localization±delocalization transition has to exist to have the integer quantum Hall eOE ect and, secondly, that we can prove that the transition does indeed exist in the limit of strong magnetic ®eld. In the language of the scaling theory of localization, the delocalized states are marginally allowed to appear in two dimensions …dˆ2 † when a magnetic ®eld exists. Later it was revealed that the marginal situation is realized as the delocalized region coalescing into a single point (the centre E 0 ) of each Landau level on the energy axis, where the localization length (proportional to

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“…The band structure of a single layer of the t phase, calculated with the extended HuÈ ckel method, contains a¯at-bottomed band (Terzis et al 1991).…”

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confidence: 99%

Transport around criticalities: Localization-delocalization and paramagnetic-ferromagnetic transitions

Aoki

2001

Philosophical Magazine B

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“…[4] [5] In such cases the interaction of the magnetic field with the electronic structure is generally orbital in form, and the magnetic field induced phases are therefore dependent on field direction due to the low dimensional topology of the Fermi surface. In marked contrast to conventional Fermi surface nesting behavior, we present a description of a new type of field induced metal-to-insulator transition in an organic metal.Our main experimental result is the universal behavior of the resistance of all isostructural members of the τ -phase class of organic conductors [6,7] in very high (B > 36T ) magnetic fields. Here we find a first order metal-toinsulator transition above a temperature-dependent and hysteretic threshold field, B th .…”

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“…Our main experimental result is the universal behavior of the resistance of all isostructural members of the τ -phase class of organic conductors [6,7] in very high (B > 36T ) magnetic fields. Here we find a first order metal-toinsulator transition above a temperature-dependent and hysteretic threshold field, B th .…”

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High-magnetic-field-induced insulating phase in an organic conductor

et al. 2003

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We report electrical transport, skin depth, and magnetocaloric measurements in the τ -phase series of organic conductors at very high magnetic fields. Above 36 T these materials show a magnetic field induced first order phase transition from a metallic to an insulating state. The transition, which is a bulk thermodynamic phenomenon, does not follow the conventional prescription for field induced phase transitions in organic conductors.In low-dimensional metals, high magnetic fields often act to reduce the effective dimensionality, thereby inducing a metal-to-density wave state [1]. This is most evident in quasi-one dimensional Bechgaard and related organic salts [2] [3]. Even in the case of quasi-two dimensional materials, the magnetic field plays an important role in determining the ground state properties. [4] [5] In such cases the interaction of the magnetic field with the electronic structure is generally orbital in form, and the magnetic field induced phases are therefore dependent on field direction due to the low dimensional topology of the Fermi surface. In marked contrast to conventional Fermi surface nesting behavior, we present a description of a new type of field induced metal-to-insulator transition in an organic metal.Our main experimental result is the universal behavior of the resistance of all isostructural members of the τ -phase class of organic conductors [6,7] in very high (B > 36T ) magnetic fields. Here we find a first order metal-toinsulator transition above a temperature-dependent and hysteretic threshold field, B th . An overview of the fieldtemperature phase diagram of these materials is shown in Fig.

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“…Το άλας (EDOVDT-TTF) x Cu(SCN) 2 είναι ημιαγώγιμο με σ ΚΤ =1.5 (Ω.αη)-1 [231]. Η εξάρτηση της σχετικής αντίστασης από τη θερμοκρασία φαίνεται στο Σχήμα 4.6α.…”

Section: υπολογισμός της ηλεκτρονικής δομής των ενεργειακών ζωνώνunclassified

“…Συγκεκριμένα από τους 300 μέχρι τους 180 Κ περίπου είναι ημιαγώγιμο, στους 180 Κ γίνεται μεταλλικό και αυτή η συμπεριφορά διατηρείται μέχρι τους 37 Κ περίπου, όπου συμβαίνει μετάβαση μετάλλου-ημιαγωγού (Σχήμα 4.6β). Η μεγάλη ποικιλία στην αγωγιμομετρική συμπεριφορά του άλατος μπορεί να εξηγηθεί με την Το άλας (EDOP-DSDTF) {ΒΈ 4 [231] κρυσταλλώνεται στο τρίκλινες σύστημα, space group PI, με a=8.377, b=8.631 και c=l 1.427 À, α=97.06, β=101.31 και γ=114.25°, V=719.28 A3, Ζ=2, R=0.042. Η κρυσταλλική δομή του άλατος φαίνεται στο Σχήμα 4.9α.…”

Section: υπολογισμός της ηλεκτρονικής δομής των ενεργειακών ζωνώνunclassified

Οργανικα Αγωγιμα Υλικα Που Βασιζονται Σε Ετεροκυκλικες Ενωσεις Με Οξυγονο Θειο Σεληνιο Και Αζωτο

Λαγουβαρδοσ¹

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ΠΕΡΙΕΧΟΜΕΝΑ Εισαγωγή ΚΕΦΑΛΑΙΟ 1: ΓΕΝΙΚΟ ΜΕΡΟΣ Α. Η ανακάλυψη των οργανικών αγώγιμων υλικών 3 Β. Η ανάπτυξη των οργανικών υπεραγωγών 6 Γ. Στοιχεία Φυσικής των χαμηλοδιάστατων συστημάτων Θεωρία ζώνης Αστάθειες στα μονοδιάστατα στερεά Θεωρία BCS για την υπεραγωγιμότητα Δ. Σχέση δομής και υπεραγωγιμότητας στα οργανικά αγώγιμα υλικά 20 Διαστατικότητα και υπεραγωγιμότητα. Πίεση και υπεραγωγιμότητα 20 Ογκος στοιχειώδους κυψελίδας και υπεραγωγιμότητα ή δραστικός όγκος και υπεραγωγιμότητα Μαλακό πλέγμα και υπεραγωγιμότητα Συμπεράσματα Ε. Σύνθεση νέων αγώγιμων και υπεραγώγιμων οργανικών υλικών βασισμένων σε παράγωγα του TTF Παράγοντες που επηρεάζουν την ικανότητα των π-δοτών να σχηματίζουν αγώγιμα στερεά Νέοι π-δότες Νέα ανιόντα ΣΤ. Σκοπός της διατριβής Δότες που περιέχουν μια αιθυλενοδιοξυομάδα Δότες με τον ανθρακικό σκελετό του BEDT-TTF (ή ET) Δότες με μεγάλο μήκος ΚΕΦΑΛΑΙΟ 2: ΠΑΡΑΣΚΕΥΗ ΚΑΙ ΧΑΡΑΚΤΗΡΙΣΜΟΣ ΤΩΝ π-ΔΟΤΩΝθειόνη 53 Δ. Συμμετρικοί και ασύμμετροι π-δότες Ε. Χαρακτηριστικά των νέων π-δοτών Δυναμικά οξείδωσης Cis και trans μορφή του δότη BEDT-D(ST)F ΚΕΦΑΛΑΙΟ 3: ΠΑΡΑΣΚΕΥΗ ΚΑΙ ΜΕΛΕΤΗ ΤΩΝ ΡΙΖΙΚΩΝ ΑΛΑΤΩΝ 76 Α. Μέθοδοι παρασκευής Χημική μέθοδος Ηλεκτροχημική μέθοδος Β. Μελέτη των ριζικών αλάτων 79 Κρυσταλλογραφική μελέτη Αγωγιμομετρική μελέτη Φασματοσκοπία ESR Φασματοσκοπία Raman συντονισμού Υπολογισμός της ηλεκτρονικής δομής των ενεργειακών ζωνών ΚΕΦΑΛΑΙΟ 4: ΑΠΟΤΕΛΕΣΜΑΤΑ ΚΑΙ ΣΥΖΗΤΗΣΗ 86 Α. Αλατα δοτών που περιέχουν μια αιθυλενοδιόξυ-ομάδα Αλατα διαφόρων μορφών Αλατα τ-μορφής Β. Αλατα των δοτών BEDT-D(ST)F και BEDT-STTF 108 Γ. Αλατα του δότη Ρ-S,S-DMEDT-TTF

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Crystal structures and properties of some cation radi EDOMDTTTF, EDOVDTTTF, EDOBTTF, EDOPDSDTF, EDODMPTTF, BEDTTTF and BMDTTTF

Cited by 19 publications

References 1 publication

Transport around criticalities: Localization-delocalization and paramagnetic-ferromagnetic transitions

Transport around criticalities: Localization-delocalization and paramagnetic-ferromagnetic transitions

High-magnetic-field-induced insulating phase in an organic conductor

Οργανικα Αγωγιμα Υλικα Που Βασιζονται Σε Ετεροκυκλικες Ενωσεις Με Οξυγονο Θειο Σεληνιο Και Αζωτο

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