Structural, magnetic phase transitions and superconductivity in Ba(Fe1-xTMx)2As2 (TM=Co, Ni, Cu, Co / Cu, Rh and Pd) single crystals

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Date/Time:Thursday, 22 Oct 2009 from 4:10 pm to 5:00 pm
Location:Physics 5
Phone:515-294-0849
Channel:Condensed Matter Physics
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Photo
Ni Ni (Iowa State University and Ames Laboratory)

BaFe2As2 single crystals undergo strongly coupled tetragonal to orthorhombic / paramagnetic to antiferromagnetic phase transitions at 134 K and can become superconducting under doping [1,2,3]. To study the correlations between the structural / magnetic phase transitions and the superconductivity, seven transition metal electron doped series : Ba(Fe1-xTMx)2As2 (TM=Co, Ni, Cu, Co / Cu, Rh and Pd) were grown and characterized by microscopic, transport and thermodynamic measurements. It was found that the structural and magnetic phase transitions (upper transitions) at 134 K in pure BaFe2As2 were monotonically suppressed and increasing separated for all these dopants, in addition, superconductivity could be stabilized with a Tc to a maximum of ~ 24 K and then being suppressed back with doping [4]. The analysis of the temperature-dopant concentration (T-x) and temperature-extra electron (T-e) phase diagrams for all these series showed that whereas the upper, structural and magnetic, phase transitions were suppressed in a grossly similar manner with increasing doping concentration for all these dopants, the superconducting dome act quite differently, scaling with e: the number of extra electrons added by the doping, at least on the overdoped side of the superconducting dome [5].


[1] Marianne Rotter, et al. Phys. Rev. B 78, 020503(R) (2008)
[2]: Marianne Rotter, et al., Phys. Rev. Lett. 101, 107006 (2008)
[3]: A. S. Sefat, et al., Phys. Rev. Lett. 101, 117004 (2008)
[4]: N. Ni, et al., Phys. Rev. B 78, 214515 (2008)
[5]: P. C. Canfield, et al., Phys. Rev. B 80, 060501 (2009)