Study of Spin System with t_<2g> Orbital Degeneracy for Ladder and Chain

概要

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Bf['ective spin Hatniltoniatts with Z2. orlaital degeneracy have been investigated theoretically.XX'e assttme tluat a d electron occtrpies one of doubly degeneratte d.. and cl... orbitals which havethe lowest energy in atotaaic level. Tlue orbit?xl degrees of f'reedouaa are represented as Ising iso-spinoperators 1.cecatrse of' the sytaarnetry of the orloital characters. NX7e apply the H?tnailtonians to 21,ladder and a claain lattices and investigttte the taaodels trsing the exact diagonatlization. For theladder ttaodel, a spin gap opens above a finite valtte of flue spin exch?tnge cotrpling on rung, xvhicluis qtralitatively difl'erent fronn the lstdder uaaodel xvith siragle or1.cit?rl. For the charirr naodel, thespin gulp belaavior is obserxxed in the trtaiforraa spin correlation ?rt low teutaperattrre. Origita of' thesjcin gap is 21 spira-ditner triggered Joy the occturrence of' the ferr'ouaaagnetic orloital ordering, wlaichstrggests a nexv uaaechanisnaa of' the spin gap f'ortaaation.
社団法人日本物理学会の論文
1999-01-15