Evidence for it came from the Stern-Gerlach Experiment.
The Hamiltonian in the Heisenberg model of ferromagnetism is a sum of the product of a coupling constant and operators of this property.  For one type of particle, the operator for this property can be found by multiplying h bar over two by the Pauli matrix.  A g-factor of approximately two is used in the expression for an electron's magnetic moment resulting from this property. This property must differ for two electrons in the same orbital. Evidence for it came from the Stern-Gerlach Experiment. An electron can have plus or minus one half as values of this property's quantum number.  For 10 points, name this intrinsic angular momentum of a particle.
The Hamiltonian in the Heisenberg model of ferromagnetism is a sum of the product of a coupling constant and operators of this property.  
spin [accept spin angular momentum]