One class of materials named for this quantity exhibits frustrated magnetism and is exemplified by dysprosium (10[1])titanate. Interactions between two of these quantities are described in the Sherrington–Kirkpatrick model, which models a set of magnetically-disordered materials named for this quantity. The Ising model of ferromagnetism uses a lattice where each atom is assigned a value of this quantity. This quantity names “ice” and “glass” magnetic states in condensed matter physics. Silver atoms were fired through a magnetic field to demonstrate this quantity’s quantization in the Stern–Gerlach experiment. Particles that obey the Pauli exclusion principle have a half-integer value of this quantity and are known as fermions. For 10 points, name this intrinsic angular momentum of a particle. ■END■