- #1
kelly0303
- 580
- 33
Hello! I am reading some papers and I often noticed that it is mentioned that a strong magnetic field is able to decouple certain angular momenta from each other. For example in this paper: https://journals.aps.org/prl/pdf/10.1103/PhysRevLett.100.023003 they present a Hamiltonian (second column on the first page) that contains terms of the form ##\gamma N\cdot S + b I\cdot S##, where S is the spin of the electron, I is the nuclear spin and N is the rotational quantum number of the molecule rotation. Then, after a strong enough magnetic field is applied, B is able to decouple S from I and N. I am not sure I understand what does this mean. If we add a magnetic field, shouldn't we just add another term to the hamiltonian so the new hamiltonian would be (ignoring the terms I ignored in the first part, too), ##\gamma N\cdot S + b I\cdot S - g\mu_B S\cdot B## i.e. the spin, S, is obviously feeling the magnetic field, but it also feels the N and I. Why would a magnetic field make the 2 terms containing I and N disappear? Can someone explain to me what this decoupling means? Thank you!