Berlin 2012 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 33: Superconductivity, Measuring Devices, Matter at Low Temperature: Poster Session

TT 33.5: Poster

Wednesday, March 28, 2012, 15:00–19:00, Poster B

Thermal expansion and magnetostriction studies on Fe-based pnictides — •Christopher Dietl¹, Norman Leps¹, Liran Wang², Ulrike Stockert³, Luminita Harnagea⁴, Sabine Wurmehl⁴, Bernd Büchner⁴, and Rüdiger Klingeler¹ — ¹Kirchhoff-Institute for Physics,University of Heidelberg, Heidelberg, Germany — ²National High Magnetic Field Laboratory, Tallahassee,Florida, USA — ³Max Planck Institute for Chemical Physics of Solids, Dresden, Germany — ⁴Leibniz Institute for Solid State and Materials Research, IFW Dresden, Dresden, Germany

We investigate the thermal expansion coefficient α and the magnetostriction β of single crystalline Ca(Fe_1−xCo_x)₂As₂ and polycrystalline RFeAsO_1−xF_x. The data are obtained by means of a high-resolution capacitive dilatometer consisting of silver. For CaFe₂As₂, the SDW-type magnetic and structural phase transition causes a pronounced anomaly which shifts, splits, and broadens upon doping. The structural phase diagram is constructed and particular emphasis is given to the paramagnetic tetragonal phase where a linear temperature dependence of the length changes is observed.