ELECTRONIC-STRUCTURE AND MAGNETISM OF KMF(3) (M=MN,FE,CO,NI)

Antiferromagnetic electronic-structure calculations of the perovskite fluorides KMF(3) (M=Mn,Fe,Co,Ni) carried out using the linear muffin-t in orbital method are reported here. The calculations have successfull y predicted the insulating gaps of the systems KMnF3 and KNiF3. Howeve r, in the cases of KFeF3 and KCoF3 the insulating gap could not be acc ounted for by these calculations and this is found to be due to the fa ct that the spin-density-functional theory is inadequate to show the s plitting of the Mt(2g) bands. However, the magnetic moments obtained f rom the calculations are comparable to the experimental values, and al so the calculated density of states show good agreement overall with t he photoemission data.