Von Klitzing constant

The quantum Hall effect (or integer quantum Hall effect) is a quantum-mechanical version of the Hall effect, observed in two-dimensional electron systems subjected to low temperatures and strong magnetic fields, in which the Hall conductance σ undergoes quantum Hall transitions to take on the quantized values

where ${\displaystyle I_{\text{channel}}}$ is the channel current, ${\displaystyle V_{\text{Hall}}}$ is the Hall voltage, e is the elementary charge and h is Planck's constant. The prefactor: ${\displaystyle \nu }$ is known as the "filling factor", and can take on either integer (${\displaystyle \nu }$ = 1, 2, 3, ...) or fractional (${\displaystyle \nu }$ = 1/3, 2/5, 3/7, 2/3, 3/5, 1/5, 2/9, 3/13, 5/2, 12/5, ...) values. The quantum Hall effect is referred to as the integer or fractional quantum Hall effect depending on whether ${\displaystyle \nu }$ is an integer or fraction, respectively.

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