Verification of Wiedemann-Franz law in silver with moderate residual resistivity ratio

TL;DR

This study confirms that silver obeys the Wiedemann-Franz law at very low temperatures and high magnetic fields, demonstrating its suitability for thermal management in ultra-low-temperature physics experiments.

Contribution

The paper provides experimental verification of the Wiedemann-Franz law in silver with moderate residual resistivity ratio at low temperatures and high magnetic fields, contradicting previous reports.

Findings

Silver obeys Wiedemann-Franz law at 0.1-1.2K and up to 5T

Silver is effective for thermal links in ultra-low-temperature experiments

Contradicts earlier findings suggesting deviation from Wiedemann-Franz law

Abstract

Electrical and thermal transport were studied in a vacuum-annealed polycrystalline silver wire with residual resistivity ratio 200-400, in the temperature range 0.1-1.2K and in magnetic fields up to 5T. Both at zero field and at 5T the wire exhibits the Wiedemann-Franz law with the fundamental Lorenz number, contrary to an earlier report [Gloos, K. et al, Cryogenics 30, 14 (1990)]. Our result demonstrates that silver is an excellent material for thermal links in ultra-low-temperature experiments operating at high magnetic fields.