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Lattice Instability in the Spin Ladder System under Magnetic Field

1998; Physical Society of Japan; Volume: 67; Issue: 6 Linguagem: Inglês

10.1143/jpsj.67.1876

1347-4073

Naoto Nagaosa, Shuichi Murakami,

Theoretical and Computational Physics

We theoretically study the lattice instability in the spin-gap systems under a magnetic field. When the magnetic field is larger than a critical value h c1 , the spin gap collapses and the magnetization phenomenon occurs. We found that lattice distortion occurs in the spin ladder at an incommensurate wave vector corresponding to the magnetization, while it does not occur in the Haldane system. At low temperatures the magnetization curve shows a first order phase transition with this lattice distortion.