Metal-insulator transition in Nd1-x Eu-x NiO3 probed by specific heat and anelastic measurements

Autor(es)

Barbeta, V. B. ^[1] ; Jardim, R. F. ^[2] ; Torikachvili, M. S. ^[3] ; Escote, M. T. ^[4] ; Cordero, F. ^[5] ; Pontes, F. M. ^[6] ; Trequattrini, F. ^[7]

Afiliação do(s) autor(es)

^[1] Ctr Univ FEI, Dept Fis, BR-09850901 Sao Bernardo Do Campo - Brazil

^[2] Univ Sao Paulo, Inst Fis, BR-05315970 Sao Paulo - Brazil

^[3] San Diego State Univ, Dept Phys, San Diego, CA 92182 - USA

^[4] Univ Fed ABC, Ctr Engn Modelagem & Ciencias Sociais Aplicadas, BR-09210170 Santo Andre - Brazil

^[5] Ist Sistemi Complessi, CNR ISC, I-00133 Rome - Italy

^[6] Univ Estadual Paulista, Dept Quim, BR-17033360 Bauru - Brazil

^[7] Univ Roma La Sapienza, Dept Phys, I-00185 Rome - Italy

• Tipo de documento: Artigo Científico
• Fonte: Journal of Applied Physics; v. 109, n. 7 APR 1 2011.
• Citações Web of Science: 7

Resumo

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] (AU)

• Processo FAPESP: 05/53241-9 - Estudo de fenômenos intergranulares em materiais cerâmicos
• Beneficiário: Reginaldo Muccillo
• Modalidade de apoio: Auxílio à Pesquisa - Temático