Curie's law is valid under the commonly encountered conditions of low magnetization (μ B H ≲ k B T), but does not apply in the high-field/low-temperature regime where saturation of magnetization occurs (μ B H ≳ k B T) and magnetic dipoles are all aligned with the applied field. When the dipoles are aligned, increasing the external field will not increase the total magnetization since there can be no further alignment.