Professor Stephen Blundell

Abstract:

Muon-spin relaxation (mu SR) experiments on the conducting polymer poly(2,3-dibutoxy-1,4-phenylene vinylene) (DB-PPV) probe the dynamics of the highly mobile polarons created by the muon-implantation process in which muonium reacts with the polymer forming a radical state. The fluctuating spin density induced by the electronic spin defect rapidly diffusing up and down the chain leads to a characteristic relaxation, the temperature and field dependence of which permit the extraction of on-chain and inter-chain diffusion rates. These results provide information concerning: the charge-transport mechanism in DB-PPV.

Abstract:

We present a numerical simulation of angle dependent magnetoresistances oscillations(AMROs) in alpha-(BEDT-TTF)(2)KHg(SCN)(4). The nesting vector of the density wave and the magnetic breakdowngap in the low-temperature, low-magnetic-field state (LTLF) are constrained by simulations of quasi-one-dimensional (Q1D) AMRO. Quasi-two-dimensional (Q2D) AMRO simulations for the high-temperature, high-magnetic-field state (HTHF) allow the precise derivation of an ellipticity of the Q2D Fermi surface. Simulations of the field dependent AMRO demonstrate the gradual evolution of the FS from LTLF to HTHF states toward the kink transition at 23 T.

Abstract:

We present a numerical simulation of angle dependent magnetoresistances oscillations (AMROs) in α-(BEDT-TTF)2KHg(SCN)4. The nesting vector of the density wave and the magnetic breakdowngap in the low-temperature, low-magnetic-field state (LTLF) are constrained by simulations of quasi-one-dimensional (Q1D) AMRO. Quasi-two-dimensional (Q2D) AMRO simulations for the high-temperature, high-magnetic-field state (HTHF) allow the precise derivation of an ellipticity of the Q2D Fermi surface. Simulations of the field dependent AMRO demonstrate the gradual evolution of the FS from LTLF to HTHF states toward the kink transition at 23 T.

Abstract:

We have developed a model for parameterizing the shape of the quasi-two-dimensional (Q2D) Fermi surface (FS) sections found in many organic molecular metals. Using this model, we show that it is possible to extract more detail about the Q2D pocket shape from angle-dependent magnetoresistance oscillations than in the traditional approximation which assumes an elliptical FS shape. We also consider the implications for cyclotron resonance experiments.

Abstract:

We have developed a model for parameterizing the shape of the quasi-two-dimensional (Q2D) Fermi surface (FS) sections found in many organic molecular metals. Using this model, we show that it is possible to extract more detail about the Q2D pocket shape from angle-dependent magnetoresistance oscillations than in the traditional approximation which assumes an elliptical FS shape. We also consider the implications for cyclotron resonance experiments.