| Texto completo | |
| Autor(es): |
Jardim, R. F.
[1]
;
Barbeta, V. B.
[2]
;
Andrade, S.
[1]
;
Escote, M. T.
[3]
;
Cordero, F.
[4]
;
Torikachvili, M. S.
[5]
Número total de Autores: 6
|
| Afiliação do(s) autor(es): | [1] Univ Sao Paulo, Inst Fis, BR-05315970 Sao Paulo - Brazil
[2] Ctr Univ FEI, Dept Fis, BR-09850901 Sao Bernardo Do Campo - Brazil
[3] Univ Fed ABC, Ctr Engn Modelagem & Ciencias Sociais Aplicadas, BR-09210170 Santo Andre - Brazil
[4] CNR, ISC, Area Ric Roma Tor Vergata, I-00133 Rome - Italy
[5] San Diego State Univ, Dept Phys, San Diego, CA 92182 - USA
Número total de Afiliações: 5
|
| Tipo de documento: | Artigo Científico |
| Fonte: | Journal of Applied Physics; v. 117, n. 17 MAY 7 2015. |
| Citações Web of Science: | 2 |
| Resumo | |
The metal-insulator (MI) phase transition in Nd1-xEuxNiO3, 0 <= x <= 0.35, has been investigated through the pressure dependence of the electrical resistivity rho(P, T) and measurements of specific heat C-P(T). The MI transition temperature (T-MI) increases with increasing Eu substitution and decreases with increasing pressure. Two distinct regions for the Eu dependence of dT(MI)/dP were found: (i) for x <= 0.15, dT(MI)/dP is nearly constant and similar to -4.3 K/kbar; (ii) for x >= 0.15, dT(MI)/dP increases with x and it seems to reach a saturation value similar to -6.2 K/kbar for the x = 0.35 sample. This change is accompanied with a strong decrease in the thermal hysteresis in rho(P, T) between the cooling and warming cycles, observed in the vicinity of T-MI. The entropy change (Delta S) at T-MI for the sample x = 0, estimated by using the dT(MI)/dP data and the Clausius-Clapeyron equation, resulted in Delta S similar to 1.2 J/mol K, a value in line with specific heat measurements. When the Eu concentration is increased, the antiferromagnetic (AF) and the MI transitions are separated in temperature, permitting that an estimate of the entropy change due to the AF/Paramagnetic transition be carried out, yielding Delta S-M similar to 200 mJ/mol K. This value is much smaller than that expected for a s - 1/2 spin system. The analysis of rho(P, T) and C-P(T) data indicates that the entropy change at T-MI is mainly due to the electronic delocalization and not related to the AF transition. (C) 2015 AIP Publishing LLC. (AU) | |
| Processo FAPESP: | 13/07296-2 - CDMF - Centro de Desenvolvimento de Materiais Funcionais |
| Beneficiário: | Elson Longo da Silva |
| Modalidade de apoio: | Auxílio à Pesquisa - Centros de Pesquisa, Inovação e Difusão - CEPIDs |