### Session R37: Focus Session: Fe-based Superconductors: Nematicity and Related Phenomena

2:30 PM–5:30 PM, Wednesday, March 20, 2013
Room: 345/346

Sponsoring Units: DMP DCOMP
Chair: Andrey Chubukov, University of Wisconsin

Abstract ID: BAPS.2013.MAR.R37.4

### Abstract: R37.00004 : In-plane structural and electronic anisotropy in de-twinned CaFe$_2$As$_2$ compounds

3:06 PM–3:18 PM

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#### Authors:

Erick Blomberg
(The Ames Laboratory, Ames, IA 50011, USA)

M.A. Tanatar
(The Ames Laboratory, Ames, IA 50011, USA)

S. Ran
(The Ames Laboratory, Ames, IA 50011, USA)

S.L. Bud'ko
(The Ames Laboratory, Ames, IA 50011, USA)

P.C. Canfield
(The Ames Laboratory, Ames, IA 50011, USA)

R. Prozorov
(The Ames Laboratory, Ames, IA 50011, USA)

In-plane structural and electronic anisotropy has been studied in a wide range of iron-based superconductors by detwinning via uniaxial stress or strain [1]. In particular, materials based on BaFe$_2$As$_2$ ("112") are among the most studied systems, where different dopants, annealing protocols and different flux growths were extensively explored. However CaFe$_2$As$_2$ remains a much less studied compound and it exhibits properties quite different from Ba-based 122's [2]. Here we report polarized-light microscopy and electric transport measurements of strain-detwinned CaFe$_2$As$_2$ compounds. Our results reveal unusual evolution of the structural, electronic and magnetic properties dependent on annealing, growth from Sn flux vs FeAs flux, and doping, as compared to BaFe$_2$As$_2$. Among the key observations are the differences in twin domain evolution, and a hysteresis in structural and electronic anisotropy upon warming and cooling. This work was supported by the Department of Energy Office of Science, Basic Energy Sciences under Contract No. DE-AC02-O7CH11358.\\[4pt] [1] M. A. Tanatar, E. C. Blomberg, et. al. Phys. Rev. B 81, 184508 (2010).\\[0pt] [2] S. Ran, et. al. Phys. Rev. B 85, 224528 (2012).

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2013.MAR.R37.4