Quantum spin flop transition in nanowire ferrimagnets

Recently a ferrimagnetic quantum spin chain consisting of Ni and Mn ions has been synthesized to create a new type of magnet with a long life time, based on the Glauberʹs slow dynamics. Its magnetic properties are well described by the (s,S)=(1,2) spin alternating chain model, with single-ion anisotropies D1 and D2 at Ni and Mn sites, respectively. Thus we investigate the magnetization process of this model, using the numerical exact diagonalization and finite-size scaling technique. It predicts a new field-induced quantum phase transition between two different Tomonaga–Luttinger liquid phases; TLL1 and TLL2 for some negative values of D1 and D2. This transition corresponds to a quantum version of the spin flop. Some typical phase diagrams are presented.