Dresden 2014 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 55: Correlated Electrons: Quantum-Critical Phenomena - Experiment II
TT 55.1: Vortrag
Mittwoch, 2. April 2014, 11:15–11:30, HSZ 204
Electronic structure investigations in β-LuAlB4 — •Pascal Reiss1, Sven Friedemann1, Michael Sutherland1, Swee K. Goh2, Kentaro Kuga3, Eoin O’Farrell3, Hisatomo Harima4, Satoru Nakatsuji3, and F. Malte Grosche1 — 1Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, United Kingdom — 2Chinese University of Hong Kong, Shatin, N.T., Hong Kong — 3Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan — 4Kobe University, Kobe 657-8501, Japan
The β-phase of YbAlB4 is the first Yb based heavy fermion compound which features both superconductivity and quantum critical behaviour without the need of tuning by magnetic field, pressure or doping [1]. Quantum oscillation (QO) measurements can help decide whether at low temperature the relevant 4f states in YbAlB4 form a band and contribute to the Fermi surface, or whether they should be regarded as localised [2]. Here, we use β-LuAlB4 as a reference compound: both compounds have the same crystal structure, and Lu features a full 4f shell, which prevents the f-states from contributing to the Fermi surface volume. We present QO measurements on β-LuAlB4 and compare them to detailed calculations based on LDA-DFT. Whereas our calculations agree in detail with the observed frequencies and their angular dependence in β-LuAlB4, they differ significantly from the QO spectra observed in β-YbAlB4. These findings strongly suggest itinerant 4f electron character in YbAlB4 further supporting the conclusions reported in [2].
S. Nakatsuji et al, Nature Phys. 4, 603 (2008)
E.C.T. O’Farrell et al, PRL 102, 216402 (2009)