Theoretical study of the magnetic ordering in rare-earth compounds with face-centered-cubic structure

 

We present a detailed theoretical study of the magnetic ordering in heavy rare-earth compounds with a face-centered-cubic structure. In addition to the exchange interactions which are counted up to the third nearest neighbors, the effect of the dipolar interactions and magnetic anisotropic effect are also included in our model Hamiltonian. The interactions parameters are obtained from first-principles band-structure calculations by fitting the total energies of different magnetic configurations to the Heisenberg Model. Thus from utilizing the Monte Carlo simulations, we explained the formation of different magnetic structures in the rare-earth compounds.

...To do this, we carried out total-energy calculations on four different magnetic orderings of the fcc structure. One of them is ferromagnetic (FM) ordering as ErN has, the other three are   antiferromagnetic (AFM) orderings, as shown in Ref. 8. In the first AFM ordering (AFM I) which is called face-centered first kind, the ferromagnetic sheet is in the x-y ( or x-z,y-z )  plane. CeBi was found to have this kind of AFM ordering. In the second AFM ordering (AFM II), face-centered second kind (type I) , the ferromagnetic sheet is along the f [111] plane. Most of the RX compounds, including ErAs, were found to have this Mn–O-type AFM structure. The third AFM structure (AFM III) is a modification of the first one. In fact, more AFM orderings can be found in Ref. 9, but the four structures we chose are enough for us to get the exchange parameters.

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