Professor Stephen Blundell: Publications

Synthesis and Characterization of Ru‐Doped n = 1 and n = 2 Ruddlesden—Popper Manganates.

ChemInform Wiley 33:48 (2002) 7-7

Authors:

Daniel J Gallon, Peter D Battle, Stephen J Blundell, Jonathan C Burley, Amalia I Coldea, Edmund J Cussen, Matthew J Rosseinsky, Christopher Steer

Muon-spin relaxation study of anisotropic charge carrier motion in polyphenylene vinylene-based polymers

Journal of Physics Condensed Matter 14:42 (2002) 9987-9995

Authors:

SJ Blundell, FL Pratt, IM Marshall, CA Steer, W Hayes, A Husmann, C Fischmeister, RE Martin, AB Holmes

Abstract:

Muon-spin relaxation (μSR) experiments on the conducting polymers poly(2, 3-dibutoxy-1, 4-phenylene vinylene) and poly(2, 5-bis(dimethyloctylsilyl)-1, 4-phenylene vinylene) 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 dependences of which permit the extraction of intrachain and interchain diffusion rates. The intrachain diffusion rate decreases with temperature and can be fitted to a model of phonon-limited transport. The interchain diffusion rate increases with temperature and can be fitted to an activated temperature dependence.

Synthesis and characterization of Ru-doped n = 1 and n = 2 Ruddlesden-Popper manganates

Chemistry of Materials 14:9 (2002) 3976-3983

Authors:

DJ Gallon, PD Battle, SJ Blundell, JC Burley, AI Coldea, EJ Cussen, MJ Rosseinsky, C Steer

Abstract:

Polycrystalline samples of Sr3MnRuO7 and Sr2Mn0.5Ru0.5O4 have been synthesized and characterized by neutron diffraction, dc magnetometry, and magnetotransport measurements. They are, respectively, n = 2 and n = 1 members of the Ruddlesden-Popper (RP) An+1BnO3n+1 family; both have tetragonal (I4/mmm) symmetry and a disordered distribution of Ru and Mn over the six-coordinate sites within the perovskite layers of the RP structure. Neither compound shows long-range magnetic order at 2 K, but a spin-glass transition is observed at 16 K (n = 1) or 25 K (n = 2). In the case of the n = 2 compound only, the magnetic transition is accompanied by a reduction in the zero-field electrical conductivity. A maximum magnetoresistance of ∼8% in 14 T is found in both compounds.

High-magnetic-field tests for reduced dimensionality in organic superconductors: Just how valid are the Mott-Ioffe-Regel and Anderson criteria?

INT J MOD PHYS B 16:20-22 (2002) 3078-3083

Authors:

J Singleton, PA Goddard, A Ardavan, N Harrison, SJ Blundell, JA Schlueter, AM Kini

Abstract:

The interlayer transfer integrals of various organic superconductors have been deduced using high-magnetic-field techniques. The measurements demonstrate the inappropriateness of criteria used to denote incoherent interlayer transport.

Magnetic resonances observed in the high-field magneto-optical absorption of the quantum Ising ferromagnet LiHoF4

INT J MOD PHYS B 16:20-22 (2002) 3312-3315

Authors:

RS Edwards, A Narduzzo, E Lyons, L Childress, SJ Blundell, J Singleton, RCC Ward

Abstract:

The magneto-optical absorption of the quantum Ising ferrornagnet LiHoF4 has been measured in the frequency range 38 to 140 GHz, the temperature range 0.5 to 20 K and magnetic fields of tip to 15 T. The sample was studied in two orientations, with the external magnetic field aligned perpendicular or parallel to the uniaxial direction, i.e., along the quantum and classical directions. In each case, several families of resonances are observed, including linear EPR branches and a series of non-linear fast moving resonances. We present this data and propose all interpretation for the origin of these resonances.

91̽��