Impurity Effect on Spin Ladder System

Instability in the Spin - Ladder System under

We study theoretically the lattice instability in the spin gap systems under magnetic eld. With the magnetic eld larger than a critical value h c1 , the spin gap is collapsed and the magnetization arises. We found that the lattice distortion occurs in the spin-ladder at an incommensurate wavevector corresponding to the magnetization, while it does not occur in the Haldane system. At low tempera...

A mean field theory for the spin ladder system

In the present paper, we propose a mean field approach for spin ladders based upon the Jordan-Wigner transformation along an elaborately ordered path. We show on the mean field level that ladders with even number legs open a energy gap in their low energy excitation with a magnitude close to the corresponding experimental values, whereas the low energy excitation of the odd-number-leg ladders a...

Diverging thermal expansion of the spin-ladder system (C5H12N)2CuBr4.

We present high-resolution measurements of the c(*)-axis thermal expansion and magnetostriction of piperidinium copper bromide (C5H12N)2CuBr4. The experimental data at low temperatures are well accounted for by a two-leg spin-ladder Hamiltonian. The thermal expansion shows a complex behavior with various sign changes and approaches a 1/square root T divergence at the critical fields. All low-te...

Lattice Instability in the Spin - Ladder System under Magnetic Field

We study theoretically the lattice instability in the spin gap systems under magnetic field. With the magnetic field larger than a critical value hc1, the spin gap is collapsed and the magnetization arises. We found that the lattice distortion occurs in the spin-ladder at an incommensurate wavevector corresponding to the magnetization, while it does not occur in the Haldane system. At low tempe...

Spin-ladder iron oxide: Sr3Fe2O5.