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 98.4: Topical Talk
Donnerstag, 19. März 2015, 16:45–17:15, H 0104
Developing Kondo Lattice Coherence and Quantum Criticality in YbRh2Si2 — •Steffen Wirth1, Silvia Seiro1, Stefan Kirchner2, Cornelius Krellner3, Christoph Geibel1, Qimiao Si4, and Frank Steglich1 — 1MPI for Chemical Physics of Solids, Dresden, Germany — 2MPI for Physics of Complex Systems, Dresden, Germany — 3Goethe University Frankfurt, Germany — 4Rice University, Houston, Texas, USA
Hybridization is a fundamental concept in strongly correlated electron physics. In heavy fermion metals, it may result in the generation of low-energy scales that can give rise to quantum criticality and unconventional superconductivity. An important techniques that helped shaping our understanding of nonlocal correlations – magnetic and superconducting – has been tunneling spectroscopy (STS) with its unique ability to give local, microscopic information that directly relates to the one-particle Green’s function. We investigated YbRh2Si2, an archetypal heavy fermion metal. Quantum criticality is discussed in terms of an antiferromagnetic instability and a Kondo break-down of the heavy quasiparticles. STS studies identified a hybridization-induced gap-like feature of the tunneling conductance. Here we focus on the evolution of the Kondo lattice. While the Kondo lattice starts forming already at the single-ion Kondo temperature, lattice Kondo effects dominate only at much lower temperatures. This establishes a hierarchy of energy scales. Finite-temperature signatures of the QCP are observed in field-dependent STS. Our findings are augmented by band structure calculations and transport measurements.