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• 1. [Article] Anomalous low-temperature and high-field magnetoresistance in the organic superconductor β″-(BEDT-TTF)2SF5CH2CF2SO3

  We report direct observations of anomalous magnetic-field and temperature dependences of the Shubnikov–de Haas oscillations in the organic superconductor β″-(BEDT-TTF)₂SF₅CH₂CF₂SO₃. Unlike other BEDT-TTF ...

  Citation × Citation Citation Abstract Copy Title: Anomalous low-temperature and high-field magnetoresistance in the organic superconductor β″-(BEDT-TTF)2SF5CH2CF2SO3 Author: Zuo, F., Su, X., Zhang, P., Brooks, J. S., Wosnitza, J., Schlueter, J. A., Williams, Jack M., Nixon, P. G., Winter, Rolf Walter, Gard, Gary L. Year: 1999 We report direct observations of anomalous magnetic-field and temperature dependences of the Shubnikov–de Haas oscillations in the organic superconductor β″-(BEDT-TTF)₂SF₅CH₂CF₂SO₃. Unlike other BEDT-TTF based organic superconductors, a nonmetallic temperature dependence of the background magnetoresistance is clearly observed. It is speculated that the nonmetallic behavior may arise from a partial nesting of the open orbits, similar to the field-induced density wave in the quasi-one-dimensional systems or a charge localization. The analysis of the magnetoresistance oscillations are found to deviate from the conventional Lifshitz-Kosevich description at high field and low temperatures. [S0163-1829(99)05433-8] Title: Anomalous low-temperature and high-field magnetoresistance in the organic superconductor β″-(BEDT-TTF)2SF5CH2CF2SO3 Author: Zuo, F., Su, X., Zhang, P., Brooks, J. S., Wosnitza, J., Schlueter, J. A., Williams, Jack M., Nixon, P. G., Winter, Rolf Walter, Gard, Gary L. Year: 1999 We report direct observations of anomalous magnetic-field and temperature dependences of the Shubnikov–de Haas oscillations in the organic superconductor β″-(BEDT-TTF)₂SF₅CH₂CF₂SO₃. Unlike other BEDT-TTF based organic superconductors, a nonmetallic temperature dependence of the background magnetoresistance is clearly observed. It is speculated that the nonmetallic behavior may arise from a partial nesting of the open orbits, similar to the field-induced density wave in the quasi-one-dimensional systems or a charge localization. The analysis of the magnetoresistance oscillations are found to deviate from the conventional Lifshitz-Kosevich description at high field and low temperatures. [S0163-1829(99)05433-8] Close

• 2. [Article] High-field magnetic resonant properties of β’–(ET)2SF5CF2SO3

  The charge transfer salt β′-(ET)₂SF₅CF₂SO₃, which has previously been considered a spin-Peierls material with a TSP;33 K, is examined using high-resolution high-field sub-millimeter/millimeter wave electron ...

  Citation × Citation Citation Abstract Copy Title: High-field magnetic resonant properties of β’–(ET)2SF5CF2SO3 Author: Gard, Gary L., Winter, Rolf Walter, Schlueter, J. A., Ward, Brian H., Jobiliong, E., Reyes, A. P., Kuhns, P., Krzystek, J., Brooks, J. S., Zvyagin, S. A., Rutel, B. Year: 2003 The charge transfer salt β′-(ET)₂SF₅CF₂SO₃, which has previously been considered a spin-Peierls material with a TSP;33 K, is examined using high-resolution high-field sub-millimeter/millimeter wave electron spin resonance (ESR), and nuclear magnetic resonance (NMR) techniques. A peak in the nuclear spin-lattice relaxation behavior in fields of 8 T, accompanied by a broadening and paramagnetic shift of the resonance line, indicates a phase transition at Tc~20 K. A pronounced change in the high-field ESR excitation spectra at ~24 T, observed at Tc~20 K, may indicate the onset of antiferromagnetic (AFM) correlations of the low temperature phase in β′-(ET)₂SF₅CF₂SO₃. Peculiarities of the low-temperature magnetic and resonance properties of β′-(ET)₂SF₅CF₂SO₃ are discussed. Title: High-field magnetic resonant properties of β’–(ET)2SF5CF2SO3 Author: Gard, Gary L., Winter, Rolf Walter, Schlueter, J. A., Ward, Brian H., Jobiliong, E., Reyes, A. P., Kuhns, P., Krzystek, J., Brooks, J. S., Zvyagin, S. A., Rutel, B. Year: 2003 The charge transfer salt β′-(ET)₂SF₅CF₂SO₃, which has previously been considered a spin-Peierls material with a TSP;33 K, is examined using high-resolution high-field sub-millimeter/millimeter wave electron spin resonance (ESR), and nuclear magnetic resonance (NMR) techniques. A peak in the nuclear spin-lattice relaxation behavior in fields of 8 T, accompanied by a broadening and paramagnetic shift of the resonance line, indicates a phase transition at Tc~20 K. A pronounced change in the high-field ESR excitation spectra at ~24 T, observed at Tc~20 K, may indicate the onset of antiferromagnetic (AFM) correlations of the low temperature phase in β′-(ET)₂SF₅CF₂SO₃. Peculiarities of the low-temperature magnetic and resonance properties of β′-(ET)₂SF₅CF₂SO₃ are discussed. Close

• 3. [Article] Coherent vs Incoherent Interlayer Transport in Layered Metals

  The magnetic-field, temperature, and angular dependence of the interlayer magnetoresistance of two different quasi-two-dimensional (2D) organic superconductors is reported. For k -BEDT-TTF)₂I₃, where BEDTTTF ...

  Citation × Citation Citation Abstract Copy Title: Coherent vs Incoherent Interlayer Transport in Layered Metals Author: Gard, Gary L., Wosnitza, J., Hagel, J., Qualls, J. S., Brooks, J. S., Balthes, E., Schweitzer, D., Schlueter, J. A., Geiser, U., Mohtasham, Javid, Winter, Rolf Walter Year: 2002 The magnetic-field, temperature, and angular dependence of the interlayer magnetoresistance of two different quasi-two-dimensional (2D) organic superconductors is reported. For k -BEDT-TTF)₂I₃, where BEDTTTF is bisethylenedithio-tetrathiafulvalene, we find a well-resolved peak in the angle-dependent magnetoresistance at Q590°(field parallel to the layers). This clear-cut proof for the coherent nature of the interlayer transport is absent for β″–(BEDT-TTF)₂SF₅CH₂CF₂SO₃. This and the nonmetallic behavior of the magnetoresistance suggest an incoherent quasiparticle motion for the latter 2D metal. Title: Coherent vs Incoherent Interlayer Transport in Layered Metals Author: Gard, Gary L., Wosnitza, J., Hagel, J., Qualls, J. S., Brooks, J. S., Balthes, E., Schweitzer, D., Schlueter, J. A., Geiser, U., Mohtasham, Javid, Winter, Rolf Walter Year: 2002 The magnetic-field, temperature, and angular dependence of the interlayer magnetoresistance of two different quasi-two-dimensional (2D) organic superconductors is reported. For k -BEDT-TTF)₂I₃, where BEDTTTF is bisethylenedithio-tetrathiafulvalene, we find a well-resolved peak in the angle-dependent magnetoresistance at Q590°(field parallel to the layers). This clear-cut proof for the coherent nature of the interlayer transport is absent for β″–(BEDT-TTF)₂SF₅CH₂CF₂SO₃. This and the nonmetallic behavior of the magnetoresistance suggest an incoherent quasiparticle motion for the latter 2D metal. Close

• 4. [Article] Fermiology and superconductivity at high magnetic fields in a completely organic cation radical salt

  We report specialized interplane magnetoresistance (MR) measurements on the organic superconducting compound β″–(BEDT-TTF)₂SF₅CH₂CF₂SO₃ (where BEDT-TTF is bis(ethylenedithio)tetrathiafulvalene) in both ...

  Citation × Citation Citation Abstract Copy Title: Fermiology and superconductivity at high magnetic fields in a completely organic cation radical salt Author: Brooks, J. S., Williams, V., Choi, E., Graf, D., Tokumoto, M., Uji, S., Zuo, F., Wosnitza, J., Schlueter, J. A., David, H., Winter, Rolf Walter, Gard, Gary L., Storr, K. Year: 2006 We report specialized interplane magnetoresistance (MR) measurements on the organic superconducting compound β″–(BEDT-TTF)₂SF₅CH₂CF₂SO₃ (where BEDT-TTF is bis(ethylenedithio)tetrathiafulvalene) in both the superconducting (Tc ∼ 5K) and normal states versus magnetic field direction. In the normal state, detailed angular-dependent magnetoresistance oscillation (AMRO) studies reveal peculiar features of the Fermi surface topology of this compound, and very high magnetic field studies further support the unusual nature of the electronic structure. In the superconducting state we investigate, through detailedAMRO measurements, the anomalous MR peak that appears within the superconducting field-temperature phase diagram. Our results reveal a direct connection between the superconducting state determined from purely in-plane field, and the vortex lattice produced by the inter-plane magnetic field. We also describe several unique sample rotation instruments used in these high field experiments, including the use of dysprosium pole pieces in combination with a 45 T hybrid magnet to carry out measurements at the highest steady-state resistive magnetic field (47.8 T) yet achieved. Title: Fermiology and superconductivity at high magnetic fields in a completely organic cation radical salt Author: Brooks, J. S., Williams, V., Choi, E., Graf, D., Tokumoto, M., Uji, S., Zuo, F., Wosnitza, J., Schlueter, J. A., David, H., Winter, Rolf Walter, Gard, Gary L., Storr, K. Year: 2006 We report specialized interplane magnetoresistance (MR) measurements on the organic superconducting compound β″–(BEDT-TTF)₂SF₅CH₂CF₂SO₃ (where BEDT-TTF is bis(ethylenedithio)tetrathiafulvalene) in both the superconducting (Tc ∼ 5K) and normal states versus magnetic field direction. In the normal state, detailed angular-dependent magnetoresistance oscillation (AMRO) studies reveal peculiar features of the Fermi surface topology of this compound, and very high magnetic field studies further support the unusual nature of the electronic structure. In the superconducting state we investigate, through detailedAMRO measurements, the anomalous MR peak that appears within the superconducting field-temperature phase diagram. Our results reveal a direct connection between the superconducting state determined from purely in-plane field, and the vortex lattice produced by the inter-plane magnetic field. We also describe several unique sample rotation instruments used in these high field experiments, including the use of dysprosium pole pieces in combination with a 45 T hybrid magnet to carry out measurements at the highest steady-state resistive magnetic field (47.8 T) yet achieved. Close