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Metal-insulator transition in Nd$_{1-x}$Eu$_{x}$NiO$_{3}$ compounds | | M. T. Escote
; V. B. Barbeta
; R. F. Jardim
; J. Campo
; | | Rating: | Visitors: 4/5 (1 visitor) | | Date: |
22 Jun 2006 | | Journal: | Journal of Physics: Condensed Matter 18 (2006), 6117-6132 | | Subject: | Strongly Correlated Electrons; Materials Science | | Abstract: | Polycrystalline Nd$_{1-x}$Eu$_{x}$NiO$_3$ ($0 leq x leq 0.5$) compounds were synthesized in order to investigate the character of the metal-insulator (MI) phase transition in this series. Samples were prepared through the sol-gel route and subjected to heat treatments at $sim$1000 $^circ$C under oxygen pressures as high as 80 bar. X-ray Diffraction (XRD) and Neutron Powder Diffraction (NPD), electrical resistivity $
ho(T)$, and Magnetization $M(T)$ measurements were performed on these compounds. The results of NPD and XRD indicated that the samples crystallize in an orthorhombic distorted perovskite structure, space group $Pbnm$. The analysis of the structural parameters revealed a sudden and small expansion of $sim$0.2% of the unit cell volume when electronic localization occurs. This expansion was attributed to a small increase of $sim$0.003 AA{} of the average Ni-O distance and a simultaneous decrease of $sim$$- 0.5^circ$ of the Ni-O-Ni superexchange angle. The $
ho(T)$ measurements revealed a MI transition occurring at temperatures ranging from $T_{
m MI}sim 193$ to 336 K for samples with $x = 0$ and 0.50, respectively. These measurements also show a large thermal hysteresis in NdNiO$_{3}$ during heating and cooling processes suggesting a first-order character of the phase transition at $T_{
m MI}$. The width of this thermal hysteresis was found to decrease appreciably for the sample Nd$_{0.7}$Eu$_{0.3}$NiO$_{3}$. The results indicate that cation disorder associated with increasing substitution of Nd by Eu is responsible for changing the first order character of the transition in NdNiO$_{3}$. | | Source: | arXiv, cond-mat/0606573 | | Services: | Forum | Review | PDF | Favorites | |
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