J. S. Qualls

Competition between Pauli and orbital effects in a charge-density-wave system

We present angular-dependent magnetotransport and magnetization measurements on

Macroscopically inhomogeneous state at the boundary between the superconducting, antiferromagnetic, and metallic phases in quasi-one-dimensional (TMTSF)2PF6

\ensuremath{\alpha}\ensuremath{-}(\mathrm{ET}{)}_{2}\mathrm{MHg}(\mathrm{SCN}{)}_{4}

Novel phases in the field-induced spin-density-wave state in (TMTSF)2PF6

compounds at high magnetic fields and low temperatures. We find that the low-temperature ground state undergoes two subsequent field-induced density-wave-type phase transitions above a critical angle of the magnetic field with respect to the crystallographic axes. This new phase diagram may be qualitatively described assuming a charge-density-wave ground state which undergoes field-induced transitions due to the interplay of Pauli and orbital effects.

Josephson plasma resonance in k-(BEDT-TTF)2Cu(NCS)2

We report on experimental studies of the phase state and the character of phase transitions in the quasi-one-dimensional organic compound (TMTSF) 2 PF 6 in the close vicinity of the borders between the paramagnetic metal PM, antiferromagnetic insulator AF, and superconducting SC states. In order to drive the system precisely through the phase border P 0 (T 0), the sample was maintained at fixed temperature T and pressure P , whereas the critical pressure P 0 was tuned by applying the magnetic field B. In this approach, the magnetic field was used (i) for smooth and precise tuning δP = P − P 0 (thanks to a monotonic P 0 (B) dependence) and (ii) for identifying the phase composition (due to qualitatively different magnetoresistance behavior in different phases). Experimentally, we measured magnetoresistance R(B) and its temperature dependence R(B, T) in the pressure range (0 − 1) GPa. Our studies focus on the features of the magnetoresistance at the phase transitions 1 between the PM and AF phases and in the close vicinity to the superconduct-ing transition at T ≈ 1K. We found pronounced history effects arising when the AF/PM phase border is crossed by sweeping the magnetic field: the resistance depends on a trajectory which the system arrives at a given point of the P − B − T phase space. In the transition from the PM to AF phase, driven by increasing magnetic field, the features of the PM phase extends well into the AF phase. At the opposite transition from the AF to PM phase, the features of the AF phase are observed in the PM phase. These results evidence for a macroscopically inhomogeneous state, which contains macroscopic inclusions of the minority phase, spatially separated from the majority phase. When the system is driven away from the transition, the homogeneous state is restored; upon a return motion to the phase boundary, no signatures of the minority phase are observed up to the very phase boundary.

Interlayer electrodynamics in the organic superconductor κ-(BEDT-TTF)2Cu(NCS)2 (BEDT-T T F ≡ bis- ethylenedithio-tetrathiafulvalene): evidence for a transformation within the vortex state

Magnetoresistance measurements on the quasi-one-dimensional organic conductor

MAGNETO-THERMAL INSTABILITIES IN AN ORGANIC SUPERCONDUCTOR

(\mathrm{TMTSF}{)}_{2}{\mathrm{PF}}_{6}

de Haas-van Alphen oscillations in the A15 superconductor V3Si

performed in magnetic fields B up to 16 T, temperatures T down to 0.12 K and under pressures P up to 14 kbar have revealed new phases on its

The High Magnetic Field Phase Diagram of a Quasi-One Dimensional Metal

P\ensuremath{-}B\ensuremath{-}T

Flux jumps and melting of the vortex lattice in κ-(ET)2Cu(NCS)2

phase diagram. We found a new boundary which subdivides the field induced spin density wave (FISDW) phase diagram into two regions. Whereas a low-temperature region of the FISDW diagram is characterized by a hysteresis behavior typical for the first-order transitions, in a high-temperature region of the FISDW phase diagram, the hysteresis was found to disappear. We also found that the temperature dependence of the resistance (at a constant

Crystal-field Γ8-like State in Magnetically Ordered Phases of CeP: Its Anisotropy and Influence on Electronic Structure via High-Field Magnetotransport Measurements

B)