Anomalous spin waves and the commensurate-incommensurate magnetic phase transition in LiNiPO4

TitleAnomalous spin waves and the commensurate-incommensurate magnetic phase transition in LiNiPO4
Publication TypeJournal Article
Year of Publication2009
AuthorsJensen TBS, Christensen NB, Kenzelmann M, Ronnow HM, Niedermayer C, Andersen NH, Lefmann K, Jimenez-Ruiz M, Demmel F, Li J, Zarestky JL, Vaknin D
Journal TitlePhysical Review B
Volume79
Pages092413
Date Published03/01
ISBN Number1098-0121
Accession NumberISI:000264768200016
Keywordsantiferromagnetic materials, commensurate-incommensurate transformations, exchange interactions (electron), heisenberg model, lithium compounds, magnetic anisotropy, magnetic transitions, magnetoelectric effects, neutron diffraction, nickel compounds, spi
Abstract

Detailed spin-wave spectra of magnetoelectric LiNiPO4 have been measured by neutron scattering at low temperatures in the commensurate (C) antiferromagnetic (AF) phase below T-N=20.8 K. An anomalous shallow minimum is observed at the modulation vector of the incommensurate (IC) AF phase appearing above T-N. A linear spin-wave model based on Heisenberg exchange couplings and single-ion anisotropies accounts for all the observed spin-wave dispersions and intensities. Along the b axis an unusually strong next-nearest-neighbor AF coupling competes with the dominant nearest-neighbor AF exchange interaction and causes the IC structure.

URL<Go to ISI>://000264768200016
DOI10.1103/Physrevb.79.092413