2011/02/17 by S. V. Maleyev, Maleyev, S. V.
Engineering · Materials Science · Physics and Astronomy · #FOS: Physical sciences #Magnetic Properties of Alloys #Magnetic properties of thin films #Metallic Glasses and Amorphous Alloys #Strongly Correlated Electrons (cond-mat.str-el) #cond-mat.str-el
paper · pdf · doi:10.48550/arxiv.1102.3524
arxiv created 2011/02/17 · openalex publication_date 2011/02/17 · arxiv updated 2011/02/18 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
A-phase origin in cubic helimagnets (M n S i,F e G e etc) is explained. It is shown that its upper bound is a result of the spin-wave instability at H_⊥>√(8/3)Δ=HA2 where H_⊥ are the magnetic field perpendicular to the helix axis \m k and Δ the spin-wave gap respectively. The last appears due to the spin-wave interaction if one takes into account that the Dzyaloshinskii-Moriya interaction acts between different spins. The infra-red divergences (IRD) in the 1/S series for the magnetic energy at H_⊥→ HA2 are responsible for the lower A-phase boundary HA1. It is shown that the A-phase exists at all T<TC but if T≪ TC it is very narrow and can not be observed. However in the critical region just below TC its width increasing strongly. Preliminary estimations demonstrate semi-quantitative agreement with the existing experimental data. The existence of the spin-wave gap is a crucial point of our consideration. In Appendix A we present its derivation in more transparent form than in previous publication.