Wilson ratio

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Wilson ratio is a dimensionless number that compares two low‑temperature properties of a metal: its zero‑temperature magnetic susceptibility and the linear‑in‑temperature term of its electronic specific heat. In a simple, non‑interacting metal, this ratio equals 1. Real metals can deviate from 1 because electron–electron interactions change the effective mass and the density of states at the Fermi level. A Wilson ratio larger than 1 indicates stronger electronic correlations, and values above about 2 can point toward proximity to ferromagnetism. The ratio is particularly useful for characterizing strongly correlated Fermi liquids, since both quantities it compares come from the density of states at the Fermi energy.