RESUMEN
The band structure calculation for the compound Mn(2)VGa carried out using the plane wave self-consistent field package with generalized gradient approximation shows that the compound is nearly half-metallic at the equilibrium lattice parameter. However, theoretical investigations have shown that a certain percentage of atomic anti-site disorder can destroy the half-metallic nature of the sample. Hence it is important to quantify the site disorder in these systems. We have deduced the percentage of atomic anti-site disorder from the refinement of the higher angle room temperature (300 K) neutron diffraction (ND) pattern and it was observed to be roughly 8% in our sample. The field variation of resistance recorded at different temperatures shows a positive slope at low temperatures and a negative slope at higher temperatures, indicating the half-metallic character at low temperatures. The ab initio calculations predict a ferrimagnetic ground state for this system. The analysis of the magnetic structure from ND data measured at 6 K yields magnetic moment values of 1.28 µ(B) and -0.7 µ(B) for Mn and V, respectively, confirming the ferrimagnetic ordering.
RESUMEN
The crystal structure, dc and ac magnetic susceptibility, electron spin resonance and magnetoresistive behavior of Nd(x)Bi(0.5-x)Sr(0.5)MnO(3) (x = 0.1, 0.2, 0.3 and 0.4) compounds are studied. The Rietveld analysis of the XRD data shows that the samples crystallize in an orthorhombic perovskite structure, with Pbnm space group for x = 0.1 and 0.2 and Imma space group for x = 0.4 and 0.3. Magnetic studies reveal that substituting Bi with Nd collapses the robust charge ordered AFM state of Bi(0.5)Sr(0.5)MnO(3) to an inhomogeneous magnetic state. As Nd concentration increases there is a gradual appearance of cluster glass behavior. ESR studies reveal that the NBSMO system phase separates into ferromagnetic and antiferromagnetic regions below the transition temperature.