where | g ⟩ ⟩ is the ground state, g J is the Landé g-factor of the ground state and J = L + S is the total angular momentum operator (see Wigner–Eckart theorem). This correction leads to what is known as Langevin paramagnetism (the quantum theory is sometimes called Brillouin paramagnetism), that leads to a positive magnetic susceptibility. For sufficiently large temperatures, this contribution is described by Curie's law :