Doping dependent nonlinear Hall effect in SmFeAsO_1−xF_x

Abstract

We report the Hall resistivity, ρ(xy), of polycrystalline SmFeAsO(1-x)F(x) 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, ρ(xy) 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 ρ(xy)(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.

Anisotropic quasiparticle lifetimes in Fe-based superconductors

“…3,4 Since the sizes of the hole and electron FS pockets are roughly identical in the undoped system, one might expect a vanishingly small Hall coefficient and a roughly electron-hole symmetric doping dependence. However, in the intensively studied 122 systems (Ba(Fe 1−x Co x ) 2 As 2 , Ba(Fe 1−x Ni x ) 2 As 2 ) and 1111 systems (LaFeAsO 1−x F x and SmFeAsO 1−x F x ), Hall effect measurements find that transport is dominated by the electrons even for the parent compounds [5][6][7][8][9][10] . In the compensated case, this result can be explained only if the mobilities of holes and electrons are remarkably different which suggests an order of magnitude disparity in relaxation times, τ e ≫ τ h .…”

Composite formation in CdSe:Cu2Se nanocrystal films, charge transport characteristics and heterojunction performance

“…The positive Hall coefficient conrmed that both the lm samples CS20 and CS30 were p-type semiconductors and that holes were the major charge carriers in these samples. 56 The carrier mobility decreased and carrier concentration increased with increase in the Cu 2 Se wt% and with temperature.…”

Quantum oscillations in the SmFeAsO parent compound and superconducting SmFeAs(O,F)

“…The multiband description is also necessary to account for the behavior of the Hall effect data (insets of Fig. 1), whose temperature dependence is not compatible with a single-band scenario [24]. Moreover, the Hall coefficient is negative at low temperature, suggesting that it is dominated by an electron band, opposite to SdH oscillations that we associate to the hole band.…”