Single-Ion Rare Earth Anisotropy in ThMn12-Type Compounds
P. Stefański
Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17/19, 60-187 Poznań, Poland
Received: October 1, 1993
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The single-ion rare earth anisotropy was investigated in ThMn12-type compounds. For this purpose the crystal electric field parameter values were studied. In these compounds, described by formula RFe12-xTx, R = rare earth, T = Ti, V, Cr, Mo, W and Si, the T atoms have strong crystallographic site preference changing the local crystal electric field potential which "sees" the rare earth ion. The crystal electric field potentials A02 were calculated considering this site preference. The summations were performed taking into account the nearest neighborhood of the rare earth ion according to the recent results of band structure calculations. The charges of the surrounding Fe and T atoms were established applying the chemical bond model proposed by Pauling. The absolute value of A02 decreases when the content of vanadium increases in 8(i) position, which is in agreement with experimental data. Localization of Si atoms in 8(j) and 8(f) causes a decrease in A02. The 155Gd Mössbauer spectroscopy data confirm this fact. Miedema's "macroscopic" atom model of cohesion in alloys was applied for interpretation of the role of T atoms in the isomer shift and volume effects.
DOI: 10.12693/APhysPolA.85.615
PACS numbers: 75.30.Gw, 75.50.Gg