Anomalous reduction of the Lorenz ratio at the quantum critical point in YbAgGe

Abstract

We report measurements of the electrical and thermal transport on the hexagonal heavy-fermion metal YbAgGe for temperatures $T\ge$ 40 mK and in magnetic fields $H\parallel ab$ up to 14 T. This distorted Kagome-lattice system displays a series of magnetic states and a quantum critical point at $H_c=4.5$ T. The Lorenz ratio $L(T)/L_0$ displays a marked reduction only close to $H_c$. A $T$-linear contribution below 120 mK, present at all different fields, allows to extrapolate the Lorenz ratio towards T=0. At the critical field this yields $L/L_0=0.92\pm 0.03$, suggesting a violation of the Wiedemann-Franz law due to strong inelastic scattering.

7 pages including supplemental material

References in corpus (8)

• Fermi-liquid instabilities at magnetic quantum phase transitions
• Quantum Criticality in Heavy Fermion Metals
• Heavy Fermions and Quantum Phase Transitions
• Nonvanishing Energy Scales at the Quantum Critical Point of CeCoIn5
• Metamagnetic quantum criticality in Sr3Ru2O7 studied by thermal expansion
• Field-induced non-Fermi-liquid resistivity of stoichiometric YbAgGe single crystals
• Thermal conductivity in the vicinity of the quantum critical endpoint in Sr3Ru2O7
• Apparent Violation of the Wiedemann-Franz law near a magnetic field tuned metal-antiferromagnetic quantum critical point

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