2001/03/31 by J. Chovan, N. Papanicolaou, Stavros Komineas +1
Physics and Astronomy · #Advanced Condensed Matter Physics #Magnetic properties of thin films #Physics of Superconductivity and Magnetism #cond-mat.str-el #cond-mat.supr-con
paper · pdf · doi:10.1103/physrevb.65.064433
published as Phys. Rev. B 65, 064433 (2002) · 15 pages, 11 figures, 2 tables
arxiv created 2001/11/23 · openalex publication_date 2002/01/23 · arxiv updated 2009/11/30 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
The magnetic compound Ba2CuGe2O7 has recently been shown to be an essentially two-dimensional spiral antiferromagnet that exhibits an incommensurate-to-commensurate phase transition when a magnetic field applied along the c axis exceeds a certain critical value Hc. The T=0 dynamics is described here in terms of a continuum field theory in the form of a nonlinear \ensuremathσ model. We are thus in a position to carry out a complete calculation of the low-energy magnon spectrum for any strength of the applied field throughout the phase transition. In particular, our spin-wave analysis reveals field-induced instabilities at two distinct critical fields H1 and H2 such that H1<Hc<H2. Hence we predict the existence of an intermediate phase whose detailed nature is also studied to some extent.