We report an observation of a commensurate-incommensurate phase transition in the Dzyaloshinskii-Moriya spiral antiferromagnet Ba_2 Cu Ge_2 O_7. The transition is induced by an external magnetic field applied along the c-axis of the tetragonal structure, i. e., in the plane of spin rotation. Bulk magnetic measurements and neutron diffraction experiments show that the transition occurs in a critical field Hc=2.1T. Experimental results for the period of the magnetic structure and magnetization as functions of magnetic field are in quantitative agreement with our exact analytical solution for Dzyaloshinskii's model of commensurate-incommensurate transitions in spiral magnets.
@article{arxiv.cond-mat/9706146,
title = {Field-induced incommensurate-to-commensurate transition in Ba_2CuGe_2O_7},
author = {A. Zheludev and S. Maslov and G. Shirane and Y. Sasago and N. Koide and K. Uchinokura},
journal= {arXiv preprint arXiv:cond-mat/9706146},
year = {2009}
}
Comments
11 double column pages, 9 figures, submitted to PRB