Transport properties and giant Shubnikov-de Haas oscillations in the first organic conductor with metal complex anion containing selenocyanate ligand, (ET)2 T1Hg(SeCN)4

The quasi-two-dimensional organic superconductor β ′′ -(BEDT-TTF)2SF5CH2CF2SO3 (Tc ≈ 4.4 K) shows very strong Shubnikov-de Haas (SdH) oscillations which are superimposed on a highly anomalous steady background magnetoresistance, R b . Comparison with de Haas-van Alphen oscillations allow a reliable estimate of R b which is crucial for the correct extraction of the SdH signal. At low temperatures and high magnetic fields insulating behavior evolves. The magnetoresistance data violate Kohler's rule, i.e., cannot be described within the framework of semiclassical transport theory, but converge onto a universal curve appropriate for dynamical scaling at a metal-insulator transition.PACS numbers: 74.70. Kn, 71.30.+h, 72.15.Gd The electrical transport in metals can usually be described by the coherent motion of electrons in Bloch states with well-defined wave vectors. A common approach to this problem is the Boltzmann transport theory which works well for most metals and semiconductors. There are, however, a number of cases where a more complex transport mechanism is involved and where the simple approach fails [1,2]. Prominent examples are the cuprate superconductors [3] and organic metals [4] which reveal unusual normal-state properties. A central issue for these layered materials is whether the electronic conduction can be described by the coherent motion of Bloch electrons with well-defined wave vectors or whether the interlayer transport is caused by an incoherent diffusive motion of the electrons between the layers.With the assumption of a constant scattering time τ s for all charge carriers the semiclassical transport theory predicts a universal temperature and field dependence of the magnetoresistance which can be described as R(B, T )/R(0, T ) = f (B/R(0, T )), where f (x) is a universal function. This is known as Kohler's rule which holds for many metals regardless of the Fermi-surface topology [5]. Furthermore, for B parallel to the current, no magnetoresistance is expected semiclassically. Deviations from this behavior are known to occur for the interlayer transport in some organic conductors [2,4]. This was taken as an indication for incoherent transport. Other evidence for the failure of conventional transport theory is the very large low-temperature normal-state resistivity (a few Ωcm) which would correspond to meanfree paths much shorter than interatomic distances.For the quasi-two-dimensional (2D) organic metals one can assume that the interlayer transport is caused by uncorrelated tunneling events between the layers [1]. Thereby the transport is incoherent because the electrons are scattered many times within the layer before a tunneling event takes place. This may occur when the time it takes for an electron to hop between the layers is much larger than τ s , i.e.,h/t c ≫ τ s , where t c is the interlayer hopping integral. In case the intralayer momentum is conserved during the tunneling process and an interference between the wave functions on adjacent layers is possible, McKenzie and Moses [1] ...

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“…Similar observations have been reported for the SdH oscillations in other organic metals [16][17][18][19].…”

supporting

confidence: 77%

Field-Induced Metal-Insulator Transition in a Two-Dimensional Organic Superconductor

et al. 2001

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“…16, 17, 28-31. However, if we compare the present oscillations with those observed on some other highly 2D, clean organic metals [32][33][34][35], their amplitude is relatively weak and the harmonic content is low. As will be shown below, the oscillations exhibit the conventional exponential temperature and field dependence.…”

Section: Resultsmentioning

confidence: 92%

Shubnikov–de Haas oscillations and electronic correlations in the layered organic metal κ-(BETS)2 Mn[N(CN)2]3

Kartsovnik

Zverev

Biberacher

et al. 2017

Low Temperature Physics

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We present magnetoresistance studies of the quasi-two-dimensional organic conductor κ-(BETS)2Mn[N(CN)2]3, where BETS stands for bis(ethylenedithio)tetraselenafulvalene. Under a moderate pressure of 1.4 kbar, required for stabilizing the metallic ground state, Shubnikov -de Haas oscillations, associated with a classical and a magnetic-breakdown cyclotron orbits on the cylindrical Fermi surface, have been found at fields above 10 T. The effective cyclotron masses evaluated from the temperature dependence of the oscillation amplitudes reveal strong renormalization due to many-body interactions. The analysis of the relative strength of the oscillations corresponding to the different orbits and its dependence on magnetic field suggests an enhanced role of electron-electron interactions on flat parts of the Fermi surface.

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“…This means that an additional transport channel must contribute to the conductivity which presumably is caused by charge carries from the ID bands. In previous high-field SdH investigations for other organic metals comparable apparent deviations from the LK theory were reported [17,18]. It seems to be plausible that those are caused by a similar ambiguities in choosing Rb.…”

Section: P"-(et)2sfjchzcf2s03mentioning

confidence: 79%

Unusual magnetic quantum oscillations in organic metals at high magnetic fields

Wosnitza

Wanka

Hagel

et al. 2001

Physica B: Condensed Matter

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We report on Shubnikov+le Haas (SdH) and de Haa.s-van Alphen (dHvA) results for the highly two-dimensional (2D) organic superconductors K-(ET)z13(T. = 3.5 K) and~"-(ET)zSF5CH2CFzS03 (TC= 4.4 K). The SdH oscillations of both materials show an apparent deviation from the well-understood 2D dHvA signal at low temperatures and high magnetic fields. For IC-(ET)213, the mechanism leading to this behavior still needs to be clarified. For fl"-(ET)zSF~CH2CF2SOS, an anomaloussteadybackground part of the magnetoresistanceseems to accountfor the observeddiscrepancies. PACS: 74.70.Kn; 72. 15.Gd Keywords:Organic superconductors,Fermisurface,magnetotransport electronic structure [1]. These charge-transfer salts 1. Introduction are available as high-quality crystals enabling the detection of well-developed de Haas-van Alphen The organic metals and superconductors of the (dHvA) and Shubnikov4e Haas (SdH) oscillations type (ET)2X, where X represents a monovalent anion [2]. Thereby, the dHvA signals are well understood and ET (= BEDT-TTF) is the organic donor either by the conventional 3D Lifshitz-Kosevich molecule bisethylenedithio-tetrathiafulvalene, are (LK) theory [3] or by 2D theoretical models [4,5]. characterized by their quasi-two-dimensional (2D) Pronounced 2D dHvA oscillations are realized at

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Transport properties and giant Shubnikov-de Haas oscillations in the first organic conductor with metal complex anion containing selenocyanate ligand, (ET)2 T1Hg(SeCN)4

Cited by 38 publications

References 12 publications

Field-Induced Metal-Insulator Transition in a Two-Dimensional Organic Superconductor

Field-Induced Metal-Insulator Transition in a Two-Dimensional Organic Superconductor

Shubnikov–de Haas oscillations and electronic correlations in the layered organic metal κ-(BETS)2 Mn[N(CN)2]3

Unusual magnetic quantum oscillations in organic metals at high magnetic fields

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