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TT: Fachverband Tiefe Temperaturen

TT 21: Superconductivity: Poster Session

TT 21.16: Poster

Montag, 16. März 2015, 15:00–18:00, Poster B

Phase diagram of Fe-substituted BaNi₂As₂ — •Liran Wang¹, Anna Böhmer^1,2, Frédéric Hardy¹, Peter Schweiss¹, Thomas Wolf¹, and Christoph Meingast¹ — ¹Institute für Festkörperphysik,Karlsruher Institut für Technologie (KIT), 76344 Karlsruhe, Germany — ²Department of Physics and Astronomy and Ames Laboratory, Iowa State University, Ames, Iowa 50011, USA

Recently, the phosphorus doped BaNi₂As₂[1] system was found to exhibit a large increase of T_c upon suppression of the structural transition, which was attributed to a large phonon softening at the critical concentration[2]. Here, we investigate the closely related Ba(Ni₁₋₂Fe_x)₂As₂ system, mostly on the iron-rich side, using high-resolution thermal expansion, specific heat, magnetization and resistivity measurements. We find a very similar suppression of the structural transition with Fe- as with P-doping, but do not find an enhanced superconducting transition. However, both the thermal expansion and resistivity exhibit anomalously large anomalies around the critical doping region, which are shown to be of non phononic origin. We discuss similarities and differences between both Fe- and P-substituted systems.

[1] N. Kurita et al., Phys. Rev. Lett. 102, 147004 (2009).

[2] K. Kudo et al., Phys. Rev. Lett. 109, 097002 (2012).