 Electronic heat capacity

Electronic heat capacity is the contribution from electronic excitations to heat capacity. A simple normal metal with a smooth density of states near its Fermi energy has $C_{\mathrm{m}}^{\mathrm{el}}\simeq \gamma T$ well below its electron Fermi temperature. Only a narrow energy interval near the Fermi energy changes occupation on heating, explaining the small fraction of active Electrons. The Debye T-cubed test separates this contribution from lattice phonons. Interactions, a superconductivity transition or other electronic structure can invalidate a constant $\gamma$ description.