Berlin 2012 – scientific programme

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TT: Fachverband Tiefe Temperaturen

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

TT 33.13: Poster

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

Superconductivity in LiFeAs — •Johanna Brand¹, Sabine Wurmehl², Bernd Büchner², Anne Stunault³, and Markus Braden¹ — ¹II. Physikalisches Institut, Universität zu Köln — ²Leibniz-Institut, Dresden — ³Institut Laue Langevin, Grenoble

LiFeAs is a member of the family of FeAs based superconductors and is remarkable as it exhibits superconductivity without doping or application of pressure with a sizeable transition temperature, T_c=18 K. It is still an open question whether the superconducting phase in LiFeAs is characterized by spin singlets or by spin triplets. There are two ways to analyze the magnetic response in the superconducting state as a simple magnetometer study is not possible due to the superconducting shielding: Knight shift and polarized neutron diffraction experiment. We measured flipping ratios with polarized neutron diffraction to follow the spin-susceptibility across T_c. For the magnetic field applied parallel and perpendicular to the c axis we find a drop in the local spin susceptibility which is comparable to the observation for Co-doped BaFe₂As₂ suggesting a spin singlet state in LiFeAs.