Friday, March 8, 2013

1303.1677 (F. Rullier-Albenque et al.)

Longitudinal magnetoresistance in Co-doped BaFe2As2 and LiFeAs single
crystals: Interplay between spin fluctuations and charge transport in
iron-pnictides
   [PDF]

F. Rullier-Albenque, D. Colson, A. Forget
The longitudinal in-plane magnetoresistance (LMR) has been measured in different Ba(Fe_(1-x)Co_x)2As2 single crystals and in LiFeAs. For all these compounds, we find a negative LMR in the paramagnetic phase whose magnitude increases as H^2. We show that this negative LMR can be readily explained in terms of suppression of the spin fluctuations by the magnetic field. In the Co-doped samples, the absolute value of the LMR coefficient is found to decrease with doping content in the paramagnetic phase. The analysis of its T dependence in an itinerant nearly antiferromagnetic Fermi liquid model evidences a significant change of T variation above optimal doping for which the antiferromagnetic state is suppressed. The same type of analysis for the negative LMR measured in LiFeAs suggests that this compound is on the verge of magnetism and that a spin fluctuation mechanism might also be at the origin of superconductivity in this stoechiometric compound.
View original: http://arxiv.org/abs/1303.1677

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