
D. M. Pajerowski, C. R. Rotundu , J. W. Lynn, R. J. Birgeneau. Measurement of Ba(Fe1xCox)2As2 criticalmagnetic exponents for x = 0. 039, 0. 022, and 0. 021. Physical Review B, 87, p. 134507, 2013.
Abstract:
We present temperature dependent magnetic neutron diffraction measurements on Ba(Fe1−xCox)2As2 for x=0.039, 0.022, and 0.021 asgrown single crystals. Our investigations probe the behavior near the magnetic tricritical point in the (x,T) plane, xtr≈0.022, as well as systematically exploring the character of the magnetic phase transition across a range of doping values. All samples show longrange antiferromagnetic order that may be described near the transition by simple power laws, with β=0.306±0.060 for x=0.039, β=0.208±0.005 for x=0.022, and β=0.198±0.009 for x=0.021. For the x=0.039 sample, the data are reasonably well described by the order parameter exponent β=0.326 expected for a threedimensional Ising model while the x=0.022 and x=0.021 samples are near the β=0.25 value for a tricritical system in the meanfield approximation. These results are discussed in the context of existing experimental work and theoretical predictions.
Keywords:
tricritical point, Codoped BaFe2As2, iron arsenide superconductors
URL:
http://prb.aps.org/abstract/PRB/v87/i13/e134507
Posted by
Costel R Rotundu
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