Artigo
Metal-insulator transition in Nd1-x Eu-x NiO3 probed by specific heat and anelastic measurements
Fecha
2011-04-01Registro en:
Journal of Applied Physics. Melville: Amer Inst Physics, v. 109, n. 7, p. 3, 2011.
0021-8979
10.1063/1.3549615
WOS:000289952100301
WOS000289952100301.pdf
1159480346990821
0000-0001-6086-5303
Autor
Ctr Univ FEI
Universidade de São Paulo (USP)
San Diego State Univ
Universidade Federal do ABC (UFABC)
Ist Sistemi Complessi
Universidade Estadual Paulista (Unesp)
Univ Roma La Sapienza
Resumen
Oxides RNiO3 (R - rare-earth, R not equal La) exhibit a metal-insulator (MI) transition at a temperature T-MI and an antiferromagnetic (AF) transition at T-N. Specific heat (C-P) and anelastic spectroscopy measurements were performed in samples of Nd1-xEuxNiO3, 0 <= x <= 0.35. For x - 0, a peak in C-P is observed upon cooling and warming at essentially the same temperature T-MI - T-N similar to 195 K, although the cooling peak is much smaller. For x >= 0.25, differences between the cooling and warming curves are negligible, and two well defined peaks are clearly observed: one at lower temperatures that define T-N, and the other one at T-MI. An external magnetic field of 9 T had no significant effect on these results. The elastic compliance (s) and the reciprocal of the mechanical quality factor (Q(-1)) of NdNiO3, measured upon warming, showed a very sharp peak at essentially the same temperature obtained from C-P, and no peak is observed upon cooling. The elastic modulus hardens below T-MI much more sharply upon warming, while the cooling and warming curves are reproducible above T-MI. Conversely, for the sample with x - 0.35, s and Q(-1) curves are very similar upon warming and cooling. The results presented here give credence to the proposition that the MI phase transition changes from first to second order with increasing Eu doping. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3549615]