Local probing of interfacial coupling in correlated electron systems.

This research proposal focuses on thin-film correlated electron systems in which layers with different functionalities (ferromagnet, antiferromagnet, superconductor) are confronted with each other at their mutual interface. The intimate contact between two dissimilar layers leads, in general, to a proximity effect that influences the intrinsic properties of the constituent layers. In some cases the proximity effect can have a quite drastic influence. A striking example is the emergence of exchange bias as a result of the interface between a ferromagnet and an antiferromagnet: the magnetic properties of an exchange biased ferromagnet/antiferromagnet bilayer are entirely different from those of the individual layers. The resulting functionality is strongly governed by interfacial electronic coupling effects in conjunction with morphological features like interdiffusion or roughness. Very often, only the overall magnetic or superconducting behaviour can be measured and it remains very challenging to selectively study the interface area, which typically has a thickness of only a few monolayers. This project focuses on the physics of interfacial coupling in three model systems, namely ferromagnet/antiferromagnet (exchange bias), soft ferromagnet/hard ferromagnet (exchange spring), and ferromagnet/superconductor. In order to achieve the required interface selectivity, we will probe our three model systems via local probing using Mössbauer spectroscopy with conventional sources and synchrotron beams. Complementary we will also use integrating techniques like magnetization and magnetoresistance measurements.

Keywords:Superconductivity, Magnetism, Interfaces, strongly correlated electron systems

Disciplines:Condensed matter physics and nanophysics