Magnetic Exchange Interactions and Estimation of TN in CsNiF3 from First Principles

D. Leguta,band J. Ruszb,

The CsNiF3has been for long time studied as a prototype of quasi-1Dplanar ferromagnetic system. At very low temperature the studied systemis insulator and therefore the magnetic exchange interactions should de-cay very rapidly. We treated the magnetic exchange coupling within theHeisenberg model for the nearest neighbor interaction between the anti-ferromagnetically coupled Ni-chains. The influence of up to the second--nearest neighbors on the ferromagnetic exchange coupling along theNi-chains was determined. The exchange interactions were calculated for theexperimental volume by the density functional theory, within the all-electronapproach using the local density approximation for the exchange and cor-relation. The N ́eel temperature was calculated by means of the mean-fieldtheory and by the random-phase approximation method.

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