A criterion for strange metallicity in the Lorenz ratio
1Department of Condensed Matter Physics, Weizmann Institute of Science, 76100 Rehovot, Israel.
Npj Quantum Materials
|April 26, 2024
Summary
The Wiedemann-Franz law holds for non-Fermi liquids, but its low-temperature correction distinguishes strange metals. This correction, proportional to inelastic scattering, differs between Fermi and non-Fermi liquids.
Area of Science:
- Condensed matter physics
- Quantum materials
Background:
- The Wiedemann-Franz law relates thermal and electrical conductivity, often signaling Fermi liquid behavior.
- Distinguishing between Fermi liquids and exotic metallic states (strange metals) is a key challenge in condensed matter physics.
Purpose of the Study:
- To investigate the validity of the Wiedemann-Franz law in non-Fermi liquids.
- To propose a method for differentiating between various types of strange metals based on deviations from the Wiedemann-Franz law.
- To analyze the low-temperature corrections to the Lorenz ratio.
Main Methods:
- Theoretical modeling of weakly disordered non-Fermi liquids.
- Application of the quantum Boltzmann equation (QBE) approach.
- Analysis of the leading low-temperature correction to the Lorenz ratio, L(T) - L0.
Main Results:
- Non-Fermi liquids also satisfy the Wiedemann-Franz law at T → 0.
- The leading low-temperature correction, L(T) - L0, is proportional to the inelastic scattering rate.
- In Fermi liquids, L(T) - L0 ∝ -T^2, while in marginal Fermi liquids, it is L(T) - L0 ∝ -T.
- This distinction holds even with T-linear resistivity from quasi-elastic scattering.
- The transverse Lorenz ratio exhibits similar behavior.
Conclusions:
- The low-temperature correction to the Wiedemann-Franz law serves as a sensitive probe for classifying strange metals.
- The quantum Boltzmann equation provides a powerful framework for understanding transport properties in diverse metallic systems.
- This work offers a new theoretical tool to identify and characterize exotic electronic states in materials.
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