Direct Observation of a Magnetic Field Induced Commensurate-Incommensurate Transition in a Spin-Peierls System

Abstract
Using high resolution x-ray diffraction in magnetic fields up to 12.5 T, we have directly observed a magnetic field driven commensurate-incommensurate transition in a spin-Peierls compound, the organic charge transfer salt tetrathiafulvalene-Cu-bis-dithiolene (TTF-CuBDT). The field induced transition is weakly first order. The period of the incommensurate lattice modulation in the high field phase is consistent with theoretical predictions.