Mark V. Kartsovnik

π-Donor BETS Based Bifunctional Superconductor with Polymeric Dicyanamidomanganate(II) Anion Layer : κ-(BETS)2Mn[N(CN)2]3

Crystals of the bis(ethylenedithio)tetraselenafulvalene (BETS) radical cation salt with dicyanamidomanganate(II) anion, kappa-(BETS)2Mn[N(CN)2]3, were synthesized, which combine conducting and magnetic properties at ambient pressure and are superconducting (Tc approximately/= 5 K) at a moderate pressure of 0.3 kbar.

Magnetic field studies of the peculiar electronic state in the α-(BEDT-TTF)2MHg(SCN)4 family

Abstract Magnetoresistance anomalies exhibited by the members of the α-(BEDT-TTF) 2 MHg(SCN) 4 family with M=Tl, K and Rb are reviewed in connection with possible modification of their electronic structure at low temperatures. Special attention is paid to angular magnetoresistance oscillations (AMRO). The analysis of the AMRO behavior at various temperatures and magnetic fields, both below and above the phase transition temperature, enables us to get an important information about changes in the electronic band structure at the phase transition. Other peculiarities of both semi-classical magnetoresistance and quantum oscillations are discussed within the proposed model of the low-temperature state of these compounds.

Electronic phase diagrams and fermi surfaces of κ-(ET)2X, the high Tc organic superconductors

Following the introduction of κ-(ET) 2 X (X=cu[N(cN) 2 ]Cl, Cu[N(CN) 2 ]Br, CU(CN)[N(CN) 2 ], CU(NCS) 2 ) providing high-T c organic superconductors, the pressure phase diagram of k-(ET) 2 Cu[N(CN) 2 ]Cl giving the highest Tc is described, as an epitome of dramatic interplay between electronic and magnetic phases in π electron system. This demonstrates the significance of two-dimensionality, electron correlation and soft lattice. The topology of the Fermi surfaces of k-(ET) 2 X is discussed in relation to the magnetooscillatory phenomena such as Shubnikov-de Haas effect, angle-dependent magnetoresistance and thermomagnetic effects.

Superconductivity in α-(BEDT-TTF)2MHg(SCN)4 (M=K, Rb, Tl, NH4)

Abstract The layered organic metals α-(BEDT-TTF)2MHg(SCN)4 (M=K, Rb, Tl) show resistance decrease with the onset at 0.3 K, 0.5 K and 0.1 K, respectively. These decreases are suppressed by a magnetic field less than 0.2 T and considered as an occurence of superconductivity, although zero resistance is not achieved. We discuss this incomplete superconducting transition in terms of the vicinity to a superconductor-insulator transition caused by the elevated sheet resistance due to the antiferromagnetic ordering at 8 ≈ 10 K.

Angle-Dependent Magnetoresistance and Shubnikov-de Haas Oscillations in the Organic Superconductor κ-(BEDT-TTF) 2Cu[N(CN) 2]Cl under Pressure

The angle-dependent magnetoresistance oscillation (AMRO) and Shubnikov-de Haas oscillation are investigated in the layered organic superconductor κ-(BEDT-TTF) 2 Cu[N(CN) 2 ]Cl under pressure. It is found that the AMRO amplitude increases with pressure. The AMRO local maxima observed under ∼ 8 kbar are periodic in scale of tan θ. Analysis based on the generalized two-dimensional Fermi surface model reveals that the orthorhombic symmetry is broken.

Magnetoresistance anisotropy in the organic superconductor κ-(BEDT-TTF)2Cu(NCS)2

Abstract We report on systematic studies of the magnetoresistance (MR) anisotropy of κ-(BEDT-TTF) 2 Cu(NCS) 2 at ambient pressure and at P =⋍ 1.2 kbar . Prominent oscillations of the interplane MR are found under magnetic field rotating in various planes normal to the 2D bc -plane. The oscillations are mainly associated with the existence of the open Fermi surface along the K a K c -plane, revealing however somewhat complicated behaviour which is most likely due to the specifics of multiply connected Fermi surface.

The superstructure wave vector in the low-temperature electronic state of the organic conductor alpha -(BEDT-TTF)2RbHg(SCN)4 determined from angular magnetoresistance oscillations

Angular oscillations of magnetoresistance of a layered organic metal alpha -(BEDT-TTF)2MHg(SCN)4 with M=Rb have been studied at temperatures below the electronic phase transition. The derived superstructure is found to be very similar, both qualitatively and quantitatively, to that reported earlier for the salt with M=Tl. A minor series of oscillations is observed, which is the mirror reflection of the main oscillations against the (a, 2b+c)-plane. The data obtained for M=K reveal significant quantitative differences from the Rb and Tl compounds.

Magnetotransport evidence for irreversible spin reorientation in the collinear antiferromagnetic state of underdoped Nd2-xCexCuO4

We make use of the strong spin-charge coupling in the electron-doped cuprate

Hierarchy of the density-wave states and superconductivity in the organic conductor α-(BEDT-TTF) 2 KHg(SCN) 4

\mathrm{Nd}_{2-x}\mathrm{Ce}_x\mathrm{CuO}_4

Hierarchy of the density-wave states and superconductivity in the organic conductor α-(BEDT -TTF )2KHg (SCN )4

to probe changes in its spin system via magnetotransport measurements. We present a detailed study of the out-of-plane magnetoresistance in underdoped single crystals of this compound, including the nonsuperconducting,