-
[show abstract]
[hide abstract]
ABSTRACT: 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.
Journal of Physics Condensed Matter 05/2009; 21(19):195409. · 2.55 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The crystal structure, dc and ac magnetic susceptibility, electron spin resonance and magnetoresistive behavior of NdxBi0.5−xSr0.5MnO3 (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 Bi0.5Sr0.5MnO3 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.
Journal of Physics Condensed Matter 04/2009; 21(19):195409. · 2.55 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We have studied structure, transport, and magnetic properties of NdxBi0.5−xSr0.5MnO3 (NBSMO) (x = 0.2 and 0.4) through x-ray diffraction, magnetoresistance, and magnetization measurements. The Rietveld analysis of the x-ray diffraction data shows that the NBSMO crystallizes in an orthorhombic perovskite structure with Pbnm space group for x = 0.2 and Imma space group for x = 0.4. The lattice variations indicate that the highly polarizable 6s2 lone pair of Bi ion is screened and the structural changes occur in accordance with change in the average radius of A-site cations. Magnetotransport studies reveal that both samples are variable range hopping semiconductors and the hopping depends on the orientation of localized spin moment of the electrons. Magnetic studies confirm that substituting Bi with Nd collapses the charge ordered antiferromagnetic (AFM) state of Bi0.5Sr0.5MnO3 to ferromagnetic state, with TC’s ∼ 276 and ∼ 278 K, for x = 0.2 and 0.4, respectively. The observed enhancement in colossal magnetoresistance effect in NBSMO compared to Bi0.5Sr0.5MnO3 is attributed to the presence of competing ferromagnetic and charge ordered AFM state.
Journal of Applied Physics 02/2008; 103(7):07F721-07F721-3. · 2.17 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We have investigated the spontaneous magnetization exhibited in Nd0.5CaxSr0.5−xMnO3 (x = 0.1, 0.2, 0.3 and 0.4) (NCSMO) samples by measurements of magnetization and electron spin resonance. As like end members, the samples crystallize in an orthorhombic structure with Imma (x = 0.1) and Pnma (0.2, 0.3 and 0.4) space groups. Transport studies reveal that Mott small polaron hopping type conduction occurs in the insulating regime of the samples. The drop in the zero field cooled dc magnetization, a large thermal irreversibility of the field cooled and zero field cooled data and the presence of two resonance fields below the temperature T* strongly suggest the coexistence of phases in NCSMO. The occurrence of coexisting phases may be strongly influenced by the random distribution of A-site cations such as Sr and Ca, which in turn leads to delocalization of eg electrons and real space ordering of Mn3+ and Mn4+ ions.
Journal of Physics Condensed Matter 11/2007; 19(49):496221. · 2.55 Impact Factor
