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TT: Fachverband Tiefe Temperaturen

TT 110: Superconductivity: Fe-based Superconductors - 1111 and Others

TT 110.1: Vortrag

Freitag, 16. März 2018, 09:30–09:45, H 3010

Nematicity and structure in single-crystalline LaFeAsO — •Sven Sauerland¹, Francesco Scaravaggi^2,3, Liran Wang^1,2, Rhea Kappenberger^2,3, Saicharan Aswartham², Anja U.B. Wolter², Bernd Büchner^2,3, and Rüdiger Klingeler¹ — ¹Kirchhoff Institute for Physics, Heidelberg University, Germany — ²Leibniz Institute for Solid State and Materials Research Dresden IFW, Dresden, Germany — ³Institute for Solid State Physics, TU Dresden, Germany

We report the temperature dependence of the elastic shear modulus response and the thermal expansion of detwinned LaFeAsO single crystals. The orthorhombic distortion parameter is derived. While the evolution of orthorhombic distortion at T_S∼ 150 K is associated with strong uniaxial pressure dependencies in particular along the a- and b-axes as well as sizeable volume effects, our data imply much smaller lattice effects at the antiferromagnetic ordering temperature T_N. By means of the three-point bending technique in the capacitance dilatometer, we obtain the nematic susceptibility from the shear modulus response in LaFeAsO. Similar to BaFe₂As₂, the shear modulus softens well above T_S implying a Curie-Weiss-like behaviour of the nematic susceptibility. The relation of the nematic susceptibility in LaFeAsO to spin, structure and orbital degrees of freedom is discussed.