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

D. Leguta,b and J. Ruszb,c

a Institute of Physics of Materials, Academy of Sciences Ziˇzkova 22, 616 68 Brno, Czech Republic ˇ
bDepartment of Physics, Uppsala University P.O. Box 530, 751 21 Uppsala, Sweden

c Institute of Physics, Academy of Sciences Na Slovance 2, 182 21 Prague, Czech Republic


Abstract:

The CsNiF3 has been for long time studied as a prototype of quasi-1D planar ferromagnetic system. At very low temperature the studied system is insulator and therefore the magnetic exchange interactions should decay very rapidly. We treated the magnetic exchange coupling within the Heisenberg model for the nearest neighbor interaction between the antiferromagnetically coupled Ni-chains. The influence of up to the second- -nearest neighbors on the ferromagnetic exchange coupling along the Ni-chains was determined. The exchange interactions were calculated for the experimental volume by the density functional theory, within the all-electron approach using the local density approximation for the exchange and correlation. The N´eel temperature was calculated by means of the mean-field theory and by the random-phase approximation method. 


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