Fermi energy

The Fermi energy is a concept in physics, named after Enrico Fermi, that measures the energy of the least tightly held electrons in a solid. At absolute zero temperature, this value is constant for each solid and is called the Fermi energy. The Fermi level, which changes with temperature and electron count, represents an energy level with a 50 percent probability of being occupied by an electron.12

According to quantum mechanics, each energy level can only hold a limited number of electrons. Levels below the Fermi level are typically full, while those above are empty. When materials with different Fermi levels are in contact, electrons move until their Fermi levels equalize, a principle crucial for electronic devices. Fermi-Dirac statistics, developed by Fermi and P.A.M. Dirac, describe how indistinguishable particles like electrons, protons, and neutrons distribute among energy states, with no more than one particle per state. The Fermi surface is an abstract interface defining allowable electron energies in solids, crucial for understanding their thermal, electrical, magnetic, and optical properties.1345