What is Fermi energy?
The Fermi energy is the concept of quantum mechanics that refers to the energy difference between the highest and lowest occupied single-particle states in a quantum system of non-interacting fermions( like electrons, neutrons or protons) at absolute zero temperature, and this can be considered as the Fermi energy definition.
The Fermi level and Fermi energy are usually confusing terms and often used interchangeably to refer each other. Although, both the terms are equal at absolute zero temperature, different at other temperature.
Fermi energy is applied in determining the electrical and thermal characteristics of the solids. It is one of the important concepts in superconductor physics and quantum mechanics. It is used in semiconductors and insulators.
The highest energy level that an electron can occupy at the absolute zero temperature is known as the Fermi Level. The Fermi level lies between the valence band and conduction band because at absolute zero temperature the electrons are all in the lowest energy state. Due to lack of sufficient energy at 0 Kelvin, the Fermi level can be considered as the sea of fermions (or electrons) above which no electrons exist.
Fermi Energy Level
The reason for the existence of this energy level is due to Pauli’s exclusion principle which states two fermions cannot occupy that same quantum state. So, if a system has more than one fermions, each fermion has a different set of magnetic quantum numbers associated with it.
The Fermi Temperature can be defined as the energy of Fermi level divided by the Boltzmann’s constant. It is also the temperature at which the energy of the electron is equal to the Fermi energy. It is the measure of the electrons in the lower states of energy in metal.
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