FMR linewidth and resonance frequency shift caused by double exchange in doped lanthanum manganites

• Дата: 2008
• Автори: Khutsishvili, K.O., Fokina, N.P.
• Формат: Стаття
• Мова: English
• Опубліковано: НТК «Інститут монокристалів» НАН України 2008
• Назва видання: Functional Materials
• Теми: Modeling and simulation
• Онлайн доступ: http://dspace.nbuv.gov.ua/handle/123456789/134542
• Назва журналу: Digital Library of Periodicals of National Academy of Sciences of Ukraine
• Цитувати: FMR linewidth and resonance frequency shift caused by double exchange in doped lanthanum manganites // K.O. Khutsishvili, N.P. Fokina // Functional Materials. — 2008. — Т. 15, № 2. — С. 209-217. — Бібліогр.: 9 назв. — англ.

A mechanism is proposed for FMR broadening and resonance frequency shift in a ferromagnetic conducting sample (hopping conductivity) of a doped lanthanum manganite due to the double exchange (DE) under FMR conditions (i.e. by the dynamic double exchange, DDE). It has been shown that the mechanism defines the resonance frequency shift and the FMR damping coefficient ω" (the band width). This shift and broadening mechanism is effective when the variable field frequency ω is of the order of the mobile electron relaxation rate τ⁻¹. The inequality τ⁻¹>> ω" should be met for the mechanism validity. The expressions obtained for ωτ<1 agree qualitatively with the observed dependence of the FMR band width on the exciting variable field frequency as well as (under certain conditions) with experimental data on the temperature dependence of the FMR spectrum. In our opinion, this research may favor the obtaining of quantitative data on the DE constants.