Correction to the Classical Two-Species Hall Coefficient Using Twoport Network Theory

By the use of twoport network theory, the classical expression for the two-species Hall Coefficient,

R h = ( p μ p 2 - n μ n 2 ) q ( p μ p + p μ n ) 2

is, on admission of terms neglected by earlier authors, corrected to

R h = { p μ p 2 - n μ n 2 + B y 2 μ p 2 μ n 2 ( p - n ) } q { ( p μ p + p μ n ) 2 + B y 2 μ p 2 μ n 2 ( p - n ) 2 }

The new expression approximates the old when |B_y| « min {1/μ_n, 1/μ_p}. The condition of approximation establishes the range of field strength in which the classical expression is acceptable. Since the Hall Effect is part of the stock-in-trade of electrical engineers, however, it seems important that students should be aware of the correct expression.