Dresden 2014 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 35: Correlated Electrons: Quantum-Critical Phenomena - Experiment I

TT 35.4: Vortrag

Dienstag, 1. April 2014, 10:15–10:30, HSZ 204

Anomalous quantum critical behavior in a 3d itinerant magnet Sr_1−xCa_xRuO₃ — •Chien-Lung Huang^1,2, Dirk Fuchs², Markus Wissinger², Jörg Schmalian³, Rudolf Schneider², Meng-Chieh Ling³, and Hilbert von Löhneysen^1,2 — ¹Physikalisches Institut, Karlsruher Institut für Technologie, 76128 Karlsruhe, Germany — ²Institut für Festkörperphysik, Karlsruher Institut für Technologie, 76021 Karlsruhe, Germany — ³Institut für Theorie der Kondensierten Materie, Karlsruhe Institute of Technology, 76128 Karlsruhe, Germany

The magnetization M and the specific heat C of polycrystalline Sr_1−xCa_xRuO₃ were investigated as a function of the Ca substitution x. The Curie temperature T_C = 162 K of SrRuO₃ decreases linearly with increasing x. Long-range ferromagnetic (FM) order is completely suppressed above the critical concentration x_c ∼ 0.7 at which quantum critical behavior was observed. That behavior cannot be described by the conventional Hertz-Millis-Moriya thoery for an FM quantum critical point, nor by the existence of a Griffiths phase. Nevertheless, the electronic and magnetic specific heat δ C_em/T = (C_em(B)−C_em(0))/T after subtraction of the phonon contribution and the scaled magnetization M/T^β collapse onto single scaling functions F(B/T^1.25) and F(B/T^1.7), respectively. The anomalous critical behavior will be discussed in terms of magnetic inhomogeneity.