Working Group Strain Tuning of Correlated Electronic Phases

Head: Dr. Anna Böhmer

In many interesting materials the electronic properties are closely related to the structural properties of the crystal lattice. We use this connection in order to manipulate electronic properties. The easiest way to do this is to make use of the thermal expansion between sample and substrate. For example, glueing Co-doped CaFe2As2 onto glass substrate induces superconductivity in this otherwise non-superconducting material [1]. Furthermore, we use piezoactors to create an uniaxial deformation. The change of the hereby modified electrical resistance, the so-called elastoresistance, can be used to determine the nematic suszeptibility of Fe-based superconductors.

Change of the phase diagrams of Ca(Fe1-xCosub>x)2As2 induced by biaxial strain. Strain induced by high Co content leads to superconductivity in an otherwise non-superconducting material [1].


Selected Publications

(1)   A. E. Böhmer et al., Effect of Biaxial Strain on the Phase Transitions of Ca(Fe1-xCox)2As2, Phys. Rev. Lett. 118 (2017) 107002
(2)   P. Wiecki et al., Persistent correlation between superconductivity and antiferromagnetic fluctuations near a nematic quantum critical point in FeSe1−xSx, Phys. Rev. B 98 (2018) 20507
(3)   M. Chinotti et al., Ingredients for the electronic nematic phase in FeSe revealed by its anisotropic optical response, Phys. Rev. B 98 (2018) 94506
(4)   A. E. Böhmer et al., Distinct pressure evolution of coupled nematic and magnetic orders in FeSe, Phys. Rev. B 100 (2019) 64515


Members (in alphabetical order)
Name Tel
Bld.-Room E-Mail
anna böhmerGgn9∂kit edu
mehdi frachetGgn9∂kit edu