1. Paramagnetism – semiclassical
If J is not zero, then you have paramagnetism
Total angular momentum
Energy of the moment at an angle
What is the expected averaged moment along the field axis?
Langevin function
n is the volume density of moments

2. The J=1/2 case Several similarities
Two spins, J=1/2, just two states (parallel or AP), to average statistically
Several similarities
Estimate the paramagnetic susceptibility

3. Generic J and the Brillouin function

4. Lande’ g-value and effective moment
J=1/2
J=3/2
J=5
Curie law: c=CC/T

5. (2.828)2χT=g2S(S+1)