# Why is magnetization zero at optical frequencies of incident EM excitation while not at low frequencies?

In Photonic Devices by Jia-Ming-Liu, it is mentioned that magnetization at optical frequencies is zero. I know that electrons behave like an oscillator in EM fields and the amplitude of oscillation as : $$\frac{F_0}{m((\omega_0-\omega_d)^2+\gamma^2\omega_d^2)^{1/2}}$$ and decreases as the frequency of forcing function increases, so is the case ? i.e the natural frequency of oscillation is low for the electron in materials compared to optical frequencies?

At optical frequencies, the magnetization vanishes, M = 0. Consequently, for optical fields, the following relation is always true: B(r, t) = μ0H(r, t).