Multispin Raman paramagnetic resonance: Quantum dynamics of classically large angular momenta

We study the evolution of a classically large angular momentum subjected to a strong magnetic field and coupled to a spin-1/2 quantum by an anisotropic interaction. This problem arises from experiments on the fast-spin dynamics in semimagnetic quantum wells, where localized heavy holes interact with the total spin I of hundreds of magnetic ions. Despite the fact that I is very large, it is shown to obey quantum mechanics. In the case of multispin Raman paramagnetic resonance, this results in a rapid deviation of I from its initial direction in structures with various degrees of anisotropy.