Berlin 2015 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 98: Focus Session: Visualization of Heavy Fermion Formation through Scanning Tunneling Microscopy

TT 98.3: Topical Talk

Donnerstag, 19. März 2015, 16:00–16:30, H 0104

Correlated Electrons under the Microscope: from Atomic Scale Model Systems to Bulk Materials — •Peter Wahl — SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, KY16 9SS, United Kingdom

The physics of strongly correlated and heavy fermion materials is often governed by a delicate balance between magnetic order and screening of magnetic moments. Therefore it is not surprising that some of the key features of the phase diagrams of these materials can be observed already in model systems consisting of two impurities or a chain of impurities. Specifically the two impurity Kondo problem has been theoretically shown to exhibit a quantum phase transition between an antiferromagnetic singlet state and a Kondo screened phase. I will show experiments by low temperature scanning tunnelling microscopy (STM) and spectroscopy for few impurities at surfaces which aim at mimicking these model systems, specifically a realization of the two-impurity Kondo model allowing for continuous tuning of the coupling between the two magnetic atoms by attaching one of the Kondo impurities to the tip of the STM. Attaching magnetic atoms from the surface to the tip of the STM is finally shown to allow for imaging of magnetic structure in strongly correlated electron systems at the atomic scale.