Scott C Riggs et al 2009 J. Phys.: Condens. Matter 21 412201 doi:10.1088/0953-8984/21/41/412201
Scott C Riggs1, R D McDonald2, J B Kemper1, Z Stegen1, G S Boebinger1, F F Balakirev2, Y Kohama2, A Migliori2, H Chen3, R H Liu3 and X H Chen3
Show affiliationsWe report the Hall resistivity, ρxy, of polycrystalline SmFeAsO1−xFx for four different fluorine concentrations from the onset of superconductivity through the collapse of the structural phase transition. For the two more highly doped samples, ρxy is linear in magnetic field up to 50 T with only weak temperature dependence, reminiscent of a simple Fermi liquid. For the lightly doped samples with x<0.15, we find a low temperature regime characterized as ρxy(H) being both nonlinear in magnetic field and strongly temperature-dependent even though the Hall angle is small. The onset temperature for this nonlinear regime is in the vicinity of the structural phase (SPT)/magnetic ordering (MO) transitions. The temperature dependence of the Hall resistivity is consistent with a thermal activation of carriers across an energy gap. The evolution of the energy gap with doping is reported.
74.25.Fy Transport properties (electric and thermal conductivity, thermoelectric effects, etc.)
75.30.Kz Magnetic phase boundaries (including magnetic transitions, metamagnetism, etc.)
Issue 41 (14 October 2009)
Received 20 May 2009, in final form 5 August 2009
Published 24 September 2009
Scott C Riggs et al 2009 J. Phys.: Condens. Matter 21 412201
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