J. Phys.: Condens. Matter 21 (14 October 2009) 412201 (5pp) doi: 10.1088/0953-8984/21/41/412201
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Doping dependent nonlinear Hall effect in
SmFeAsO1−xFx
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
1 National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL
32310,
USA
2 National High Magnetic Field Laboratory, Los Alamos National Laboratory, MS-E536
Los Alamos, NM 87545,
USA
3 Hefei National Laboratory for Physical Sciences at Microscale and Department of Physics,
University of Science and Technology of China, Hefei, Anhui 230026,
People's Republic of China
E-mail: scr@magnet.fsu.eduAbstract.
We 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.
Print publication: Issue 41 (14 October 2009)Received 20 May 2009, in final form 5 August 2009
Published 24 September 2009
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