Temperature and Angular Dependence of Electron Paramagnetic Resonance Line in α'-NaV_2O_5

概要

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Electron spin resonance experitnents wer'e performed on a'-NaV305, a possible spin-Peierlsconapotrnd, at 9,3 and 23.5 GHz over 1.3- 700 K. An?tlyzing all factors of' the alcsorptioza line aboveT., : 34 K, strch as the valtre and the angular dependence of' the Jinewidth at high tenaperattrres,the tenaperattnre dependence of' both the linexvidtla and the resonance field, 21S well as the higlatemperature lineshape, xve find tluat the exchange-rnarrowing tlaeory closely explains these factorswhen a Iitaear Heisenberg chain with S : l /2 along the 6-axis is asstrrned, anad the arntisymtnetricexchange interactuon, I, dtt?n = (St x 8n?t) with dt;n // c-axis, between nearest-neighlcor spinson the 6-axis is adopted as the orugin of' line broadening. As lotag as the results of tlais study areconcerned, the model of V" rnagnetic ch?rins separated by nonunagnetic V" chaiuas in the ab-plane above 34 K is acceptable, However, the restrlts do not necessttrily deny a V-0-V rnolecularspin unodel that has been proposed to accotrnt f'or a new crystal strtrctture formed by only onedistinct V site, because the molecular spin naodel, as shown in recent theoretical papers, le?rdsto antiferromagnetic Heisenberg linear claains ?tlong the Z>-axis. If an effective antisyrnraaetricexchange interactuon between the molectrlar spins us proven to exist, it can be an origin of theline broadening of this conapound.
社団法人日本物理学会の論文
1998-12-15