The XXX subcase of the Heisenberg model of ferromagnetism (in short, the XXX model[1]) may be easier to understand, if not accessible to children. [1] https://

The XXX subcase of the Heisenberg model of ferromagnetism (in short, the XXX model[1]) may be easier to understand, if not accessible to children. [1] https://en.wikipedia.org/wiki/Quantum_Heisenberg_model#XXX_model https://en.wikipedia.org/wiki/Quantum_Heisenberg_model#XXX_m...