Fig. 1: Schematic representation of a trimer spin chain.
From: Fractional and composite excitations of antiferromagnetic quantum spin trimer chains
J1 and J2 represent the two different antiferromagnetic nearest-neighbor Heisenberg intratrimer and intertrimer couplings, respectively. We here consider systems with J1 ≥ J2 > 0. We will use the letters a, b, c as indicated to refer to the three spins within a given unit cell.
