Synchrotron X-ray diffraction studies of the incommensurate phase of a spin-Peierls system CuGeO₃ in strong magnetic fields

Synchrotron X-ray diffraction measurements on a spin-Peierls material CuGeO₃ in applied magnetic fields, H, up to 15 T are made. We find that the temperature, T, dependence of the incommensurate Bragg peak at a lower H is quite different from that at a higher H. At sufficiently high fields, we find that the lattice incommensurability, δ1, is almost independent of T, while at H slightly above the critical field = 12.25 T for the commensurate to incommensurate transition, δ1 decreases with increasing T. We interpret that this finding is due to a stabilization of the incommensurate state by a strong magnetic field which suppresses thermal fluctuations.