Berlin 2015 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 31: Superconductivity: Fe-based Superconductors – 122 and 111

TT 31.8: Talk

Tuesday, March 17, 2015, 11:45–12:00, H 2053

Detailed phase diagram of (Ba,Na)Fe₂As₂ — •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 a C4-symmetric magnetic phase has been discovered in (Ba_1−xNa_x)Fe₂As₂ [1], close to where the usual Spin Density Wave (SDW) transition disappears upon doping. Single crystal neutron diffraction showed that the spin orientation in this phase changes from in-plane in the C2-magnetic phase to out-of-plane [2]. Here, we re-investigate the phase diagram of this system by closely following the doping evolution of structural, magnetic and superconducting transitions by using high-resolution thermal expansion and specific heat measurements. The resulting phase diagram is shown to be considerably more complex than previously thought [1]. Differences and similarities between the Na- and K-doped [3] systems will be discussed.

[1] Avci et al., Nature Commun. 5, 3845 (2014).

[2] F.Waβer et al., unpublished.

[3] A.Böhmer et al., unpublished.