Regensburg 2013 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 59: Correlated Electrons: Quantum-Critical Phenomena - Experiments
TT 59.7: Hauptvortrag
Donnerstag, 14. März 2013, 16:45–17:15, H6
Electron Spin Resonance (ESR) close to a Quantum Phase Transition: Probing YbRh2Si2 at mK Temperatures — •Marc Scheffler1, Conrad Clauss1, Mojtaba Javaheri1, Martin Dressel1, Jörg Sichelschmidt2, Cornelius Krellner2,3, Christoph Geibel2, and Frank Steglich2 — 11. Physikalisches Institut, Universität Stuttgart, Stuttgart, Germany — 2Max-Planck-Institut für Chemische Physik fester Stoffe, Dresden, Germany — 3Physikalisches Institut, Goethe-Universität Frankfurt, Frankfurt/Main, Germany
The heavy-fermion material YbRh2Si2 is a model system for quantum criticality: the very weak antiferromagnetic order below 70 mK can be suppressed e.g. by a small magnetic field of 60 mT. This quantum phase transition results in unusual properties such as pronounced non-Fermi-liquid behavior. Previous electron spin resonance (ESR) studies on YbRh2Si2 revealed new insights concerning the spin dynamics of Kondo lattices, but were limited to temperatures above 500 mK and could not access the most interesting low-temperature regimes.
We recently developed a new measurement technique which we now use for ESR studies on YbRh2Si2 single crystals at temperatures down to 40 mK. With a set of ESR frequencies spanning 1.5-13 GHz and ESR fields as low as 30 mT, we address the temperature and field regimes close to the quantum critical point. Our results cover all three phases (antiferromagnet, non-Fermi liquid, field-induced Fermi liquid) and they open new opportunities to gain deeper insight into ESR of heavy-fermion systems and to investigate the quantum critical point.