German Conference for Research with Synchrotron Radiation, Neutrons and Ion Beams at Large Facilities

Interface effects in superconductor-ferromagnet heterostructures

18 Sept 2018, 16:00

1h 30m

Fakultät für Maschinenwesen der Technischen Universität München

Poster P4 Magnetism and quantum phenomena Poster session 2

Speaker

Ms Annika Stellhorn (Forschungszentrum Jülich GmbH, Jülich Centre for Neutron Science (JCNS-2) and Peter Grünberg Institut (PGI-4), JARA-FIT, Germany)

Description

At interfaces of ferromagnetic (F) and superconducting (S) layers proximity effects can lead to significant changes in their order parameters. When the magnetic state of the F-layer is inhomogeneous, magnetic domains can spatially confine the superconductivity in an adjacent S-layer [1]. Our goal is to obtain an understanding of such proximity effects between the two layers. Furthermore, the lateral magnetic depth profile near the S/F-interface and the dependence of the superconductivity on the magnetic configuration still have to be scrutinized.

As a prototype system we use thin film heterostructures of ferromagnetic FePd with a superconducting Nb toplayer. The heterostructures are grown using molecular beam epitaxy. To obtain FePd in the L10-ordered phase with a magnetic anisotropy perpendicular to the surface plane, growth temperatures between 230°C-350°C are used [2].

Resistivity measurements as a function of an external magnetic field H reveal the effect of the magnetic stray fields on the superconducting state. When the superposition of the stray fields and H reaches its minimum, superconductivity nucleates over the domain with magnetization direction opposite to H. To investigate the depth profile of the lateral magnetization fluctuation Grazing-Incidence Small-Angle Neutron Scattering (GISANS) is performed near the superconducting critical temperature.
[1] Z. Yang et al., Nat. Mater. 3, 793-798 (2004).
[2] V. Gehanno et al., Phys. Rev. B, 55, 12552 (1997).