Magnetic behaviour of Er1-xZrxFe2 intermetallic compounds.

In this work, the structural and magnetic properties of Er1-xZrxFe2 (0.1 ≤ x ≤ 0.4) were investigated. These compounds crystallize in the cubic MgCu2 (C15) structure, the lattice parameters decreasing with Zr content. Electronic structure calculations were performed, showing a good agreement between theory and experiment. All of the samples are ferrimagnetically ordered, presenting compensation points in the M(T) plots. The compensation point values decrease, while the Curie temperatures increase with Zr content. The experimental Fe moments at 5 K decrease with Zr content from 1.70 µB/atom for x = 0.1 to 1.55 µB/atom for x = 0.4. A non-collinear orientation of the magnetic moments was evidenced in these compounds. The magnetocaloric effect was also studied. A modest magnetocaloric effect was found for all of the samples, spreading across a wide temperature range. A maximum |ΔSM| value of 1.19 J kg(-1) K(-1) was found for the sample with x = 0.1 for an applied field change of 0-4 T. Large RCP(ΔS) values were obtained for all of the samples, mainly due to the wide δTFWHM values of the ΔSM(T) curves.

On the R 5d band polarization in rare-earth-transition metal compounds.

Magnetic measurements and band structure calculations were performed on RT(2) and RT(5) compounds, where R is a heavy rare-earth and T = Fe, Co, Ni, Al, as well as on pseudobinary compounds GdCo(2 - x)A(x) (A = Ni, Cu, Si), YFe(2 - x)V(x) and YCo(4 - x)Ni(x)B. The calculated moments per formula unit described well the experimentally determined magnetizations. By considering the 4f-5d-3d exchange interactions, we evaluate the contributions of local 4f-5d and short range 5d-3d interactions to R 5d and Y 4d band polarizations. The 4f-5d induced polarizations are proportional to the De Gennes factor and are the same for a given R and a similar type structure. The R 5d and Y 4d band polarizations induced by R 5d-T3d or Y 4d-T3d hybridizations are proportional to the number of neighbouring T atoms, to a given R, and their magnetic moments. Previous results on the matter are also discussed.