Magnetism & Superconductivity
Magnetism & Superconductivity
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Our group in 2017
Our webpage is still bit under construction...
Our research objectives
Our research objectives
Our research evolves around the superconducting and magnetic properties of materials with strongly correlated electrons. Prominent examples are the cuprate and iron arsenide high Tc superconductors for which magnetic correlations play an important role in the superconducting pairing mechanism.
Phase diagram of cuprates (left) and iron pnictides (right)
Structure of RuSr2GdCu2O8 that can be viewed as a natural multilayer of a ferromagnetic ruthenate and high Tc superconducting cuprate layers [C. Bernhard et al., Phys. Rev. B 59, 14099 (1999)].
Low magnification scanning tunneling electron microscopy (STEM) image of one of our YBa2Cu3O7/La2/3Ca1/3MnO3 (YBCO/LCMO) multilayers on a LSAT substrate [V. Malik et al., Phys. Rev. B 85, 054514 (2012)]. The individual YBCO and LCMO layers are marked by the arrows.
High magnification STEM image of one of our YBCO/LCMO multilayers [V. Malik et al., Phys. Rev. B 85, 054514 (2012)].
We also grow and study thin films and multilayers from various complex oxides. The interfaces of these artificial materials can be engineered with atomic precision which allows us to induce various kinds of electronic, magnetic and superconducting proximity-effects that arise when different interactions and orders meet at an interface. Our focus is on the combination of the cuprate high-Tc superconductors with magnetic perovskite oxides, such as the manganites that are well known for their colossal magnetoresistance (CMR) effect. Here we are especially interested in the competition between superconductivity and ferromagnetism and the resulting complex quantum states. Another example concerns the high mobility electron gas which develops at the interface between a LaAlO3 thin film and a SrTiO3 substrate. Last but not least, we are investigating the spintronic properties of organic materials in the form of oxide-organic multilayers.
Our main experimental techniques are (i) infrared and optical spectroscopy (ellipsometry), (ii) (low energy) muon spin rotation, (iii) neutron reflectometry, and (iv) resonant x-ray spectroscopy and reflectometry. Our experimental infrastructure in Fribourg is described on Equipment page. A substantial portion of our experiments are also performed at the large scale photon, neutron and muon sources of the Paul-Scherrer-Institut (PSI) in Villigen, Switzerland and at similar facilities in Europe and worldwide.
Our various collaborations with researchers in Fribourg, Switzerland and worldwide are listed in Links and Collaborations.
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