Professor Stephen Blundell: Publications

Millimetre-wave response of the organic superconductor kappa-(BEDT-TTF)(2)Cu(SCN)(2)

SYNTHETIC MET 103:1-3 (1999) 1947-1948

Authors:

JM Schrama, A Ardavan, J Singleton, SJ Blundell, W Hayes, M Kurmoo, P Day

Abstract:

A study of the electronic and superconducting properties of the organic superconductor kappa-(BEDT-TTF)(2)Cu(SCN)(2) in the millimetre-wave range is presented. The measurments are carried out using a single crystal in an unique rotating rectangular cavity. This novel technique provides information about the anisotropy of the magnetoresistance at GHz freqencies.

Muon study of the spin dynamics in the organic spin-peierls compound MEM(TCNQ)(2)

SYNTHETIC MET 103:1-3 (1999) 2034-2037

Authors:

BW Lovett, SJ Blundell, T Jestadt, FL Pratt, M Kurmoo, S Tagaki, W Hayes

Abstract:

We report a muon spin relaxation study of the organic spin-Peierls system MEM(TCNQ)(2) over the temperature range 39 mK to 200 K. Our results show a crossover from Gaussian to exponential relaxation below the spin-Peierls transition temperature. We attribute this change to the effect of a dilute set of static electronic defect spins resulting from the majority of spins freezing into a non-magnetic spin singlet state.

One-and two-dimensional angle-dependent magnetoresistance oscillations(AMROs) in kappa-(BEDT-TTF)(2)Cu(SCN)(2) in fields of up to 33 T

SYNTHETIC MET 103:1-3 (1999) 1905-1906

Authors:

MS Nam, MM Honold, C Proust, N Harrison, CH Mielke, SJ Blundell, J Singleton, W Hayes, M Kurmoo, P Day

Abstract:

Angle-dependent magnetoresistance oscillations (AMROs) in kappa-(BEDT-TTF)(2)Cu(SCN)(2) have been observed in fields of up to 33 T. AMROs due to both open and closed Fermi surface sections have been measured simultaneously for the first time in an organic metal. This provides information concerning the low temperature Fermi surface and demonstrates the absence of a spin-density wave state in this material.

Stability of the vortex lattice in ET superconductors studied by mu SR

SYNTHETIC MET 103:1-3 (1999) 1925-1928

Authors:

SJ Blundell, SL Lee, FL Pratt, CM Aegerter, T Jestadt, BW Lovett, C Ager, T Sasaki, VN Laukhin, E Laukhina, EM Forgan, W Hayes

Abstract:

Muon-spin rotation (mu SR) measurements have been used to study the vortex lattice and its instabilities in the organic superconductors kappa-ET2Cu(SCN)(2) and beta-ET2IBr2. We ascribe the field- and temperature-dependent destruction of the vortex lattice to the large anisotropy found in these materials.

Anisotropic polaron motion in conducting polymers studied by muon spin relaxation

SYNTHETIC MET 101:1-3 (1999) 323-324

Authors:

FL Pratt, SJ Blundell, BW Lovett, K Nagamine, K Ishida, W Hayes, T Jestadt, AP Monkman

Abstract:

Muon spin relaxation has been used to study the anisotropic motion of muon-generated negative polarons in polyaniline and polypyridine. Fast on-chain diffusion is found to become limited by 10 meV phenylene librations above about 150 K in polyaniline, whereas the rapid on-chain diffusion is maintained to much higher temperatures in polypyridine due to its more rigid structure.

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