This award supports theoretical research and education that focuses on the understanding of magnetic phenomena that occurs in quasi- one- and two- dimensional organic conductors. Such systems are themselves composed of complex organic molecular cations with relatively large aspect ratios. Examples of the cationic molecules include TMTSF, ET, DMET and BETS. Charge compensation is accomplished by stoichiometric inclusion of electronegative acceptor molecules such as PF6 and Cl04. These compounds exhibit a broad range of Fermi- (e.g. Magic Angles) and non-Fermi- liquid phenomena when placed in a magnetic field such as angular oscillations, field-induced spin-density wave phases, and the three dimensional quantum-hall effect. Experiments suggest additional interesting phenomenon which include reentrant superconducting phases and field-induced charge density waves. Further experimentally posited donor-specific behaviors include triplet-superconducting pairing (TMTSF) and type-IV superconductivity (Et) for which parity, spin-rotational, and time-reversal symmetries of the Cooper pairs are broken. In collaboration with experimentalists, the research will focus upon the unusual appearance of the three-dimensional quantum-Hall effect in the field-induced charge-density- and spin-density- wave phases and investigations of three-dimensional to two-dimensional to one-dimensional crossovers in both one-body and many-body phenomena. Key to the understanding of these behaviors will be an effort to develop quantum-mechanical methods that are applicable to describing the quantum-limit of a system composed of electrons on metallic planes with field-induced orbits that are small compared to interlayer spacing.
NON-TECHNICAL SUMMARY:
This award supports theoretical research and education efforts aimed at promoting an understanding of conducting and superconducting molecular materials. The research focuses on the discovery of new phenomena and new states of matter than emerge in these materials where the electronic states of electrons are restricted to one or two dimensions by virtue of the molecular building blocks from which they are made. One emphasis is to understand the conditions under which superconductivity can exist in these materials. An additional focus it to understand how these materials behave when exposed to high magnetic fields. The theoretical effort here is directly relevant to ongoing experimental efforts and will aid in the understanding of these very complicated materials. An understanding of these materials is required to assess the feasible of future nanoscale magnetic devices, such as ultra dense disks and sensing applications, and for determining the possibility of higher-temperature field-dependent superconducting materials. In parallel with the proposed researcher, educational efforts will prepare graduate and undergraduate level researchers for further efforts in the area of superconductivity.
