UNCOMPENSATION EFFECT IN A ONE-DIMENSIONAL ALTERNATING-SPIN ISING FERRIMAGNET WITH COMPETING INTERACTIONS

The characteristic short-range orders (SROs) in a one-dimensional Isin g ferrimagnet, which is composed of alternating spins with different s pin quantum numbers, Lande g-factors, and next-nearest-neighbor intera ctions, are investigated by the numerically exact calculation of a non symmetric transfer matrix. Due to the uncompensating moments, some SRO s in the system show very different characteristics from those in the uniform-spin ANNNI chain; (i) the peculiar two-peaked structure of the static spin structure factor S(q), indicating not two different SROs but the same SRO, and (ii) an unusual thermal recovery of the ferrimag netic SRO, carrying three disorder points, under a non-zero external f ield. Decaying features of the characteristic SROs and the magnetic be havior of the system with variation of external field are also discuss ed.