RESUMEN
The antiferromagnetism in Ru(2)MnGe can be suppressed by the substitution of V by Mn and ferromagnetism appears. Synchrotron-based magnetic Compton scattering experiments are used in order to investigates the role of 3d electrons in the indirect/direct exchange interactions for the appearance of ferromagnetism. A small spin moment for the itinerant electron part on the magnetic Compton profile indicates that the metallic ferromagnet Ru(2)Mn(0.5)V(0.5)Ge has a weak indirect exchange interaction between the d-like and sp-like (itinerant) electrons. This suggests that the appearance of ferromagnetism is caused by the enhancement of the direct exchange interactions between d-d electrons in the Ru(2)MnGe Heusler compound. These findings indicate that the indirect exchange interaction between itinerant electrons and localized electrons is a significant key point for the appearance of ferromagnetism in this system.
RESUMEN
The variation of the magnetic moment on Ru and Mn atoms in the Ca(0.3)Sr(0.7)Ru(1-x)Mn(x)O(3) system was investigated by the magnetic Compton scattering technique using synchrotron radiation. The Ca(0.3)Sr(0.7)Ru(1-x)Mn(x)O(3) system has ferrimagnetism with an antiferromagnetic coupling between Ru and Mn, and the dominant magnetic component changes from ferromagnetic Ru to ferromagnetic Mn at x â¼0.25 as the Mn substitution proceeds. The mechanism for the change in the magnetism of Ca(0.3)Sr(0.7)Ru(1-x)Mn(x)O(3) is discussed.
RESUMEN
The magnetism of CaRu(1-x)Mn(x)O(3)(0.2≤x≤0.9) was studied by the magnetic Compton scattering experiment. The result of the spin-polarized electron momentum density distributions (magnetic Compton profiles) and the absolute value of spin moment indicate that Mn doping introduces magnetic moments on Ru ions, and the Ru and Mn spin moments were antiferromagnetically coupled. Moreover the spin moment of Ru ions increased proportionally in the x range. These results were explained by a mixed valence model and inhomogeneous magnetic structure, where the inhomogeneous magnetic ground state in CaRu(1-x)Mn(x)O(3) would be formed by a ferrimagnetic network from the Mn(3.5+) and Ru(4.5+) clusters in the paramagnetic matrix CaRuO(3) for x<0.5 and in the antiferromagnetic matrix CaMnO(3) for x>0.5.
RESUMEN
The magnetism of CaMn(0.55)Ir(0.45)O(3) has been studied using the magnetic Compton scattering technique. The analysis of the magnetic Compton profile shows that the spin moments of Mn and Ir form an antiparallel configuration, establishing ferrimagnetism. Moreover, the experimental results indicate the existence of an orbital moment 0.2 µ(B)/f.u.. The possible model for these results has been discussed under the framework of the localized electron model by taking account of the electronic states of the Ir(4+) ion.
RESUMEN
The crystallographic, magnetic, and electric properties of CaMn(1-x)Ir(x)O(3) (0≤x≤0.6) were investigated. The lattice constants increase with increasing content of Ir. Specimens of 0.05≤x≤0.2 show antiferromagnetic behavior; however, ferromagnetism is observed for specimens of 0.3≤x≤0.6. T(N) decreases as the Ir content increases. T(N) is superseded by T(C) without passing 0 K and T(C) continues to increase in the ferromagnetic composition range. The effective moment µ(eff) decreases as the Ir content increases. The Weiss temperature is negative for small x; however, it continues to increase while changing its sign at about x = 0.3. The results were explained by assuming a mixed valence state of Mn(3+), Mn(4+), Ir(4+), and Ir(5+) ions. The composition dependence of µ(eff) could be explained qualitatively using the ion fractions estimated from the Ir content dependence of the unit cell volume. Experimental results suggest the coexistence of antiferromagnetic and ferromagnetic phases. When the volume fraction of the ferromagnetic phase dominates that of the antiferromagnetic phase, the system seems to show ferromagnetism.
