Jumping defects in a spin gap matrix.

Jumping defects in NaV2O5

The quasi 1D magnet with a ladder structure NaV2O5 demonstrates a charge order phase transition with a transformation into a spin gap singlet state. The defects in form of Na-vacancies provide unoccupied rungs of the ladder structure, or holes. The electrons from the rungs neighboring to the empty rung could jump to the unoccupied rungs, thus the Na-deficiency in Na1-xV2O5 crystals result in defects with spin and jumping degrees of freedom.

This jumping degree of freedom results in unusual magnetic and thermodynamic properties we observed in ESR, magnetic susceptibility and heat capacity measurements.

The Figure shows possible paths for electron jumps on the zig-zag charge ordered ladder structure with holes. Triangles mark the Na-vacancies

  1. A.I.Smirnov, S.S.Sosin, R.Calemczuk, V.Villar, C.Paulsen, M.Isobe, Y.Ueda, "Thermal and magnetic properties of defects in the spin-gap compound NaV2O5", Phys. Rev. B 63, 014412 (2001)