Magnetothermopower in Nd1-xEuxNiO3 compounds

Nenhuma Miniatura disponível
Citações na Scopus
Tipo de produção
Artigo de evento
Barbeta V.B.
Jardim R.F.
Escote M.T.
Dilley N.R.
Journal of Applied Physics
Título da Revista
ISSN da Revista
Título de Volume
Barbeta, V. B.; JARDIM, R. F.; ESCOTE, M. T.; DILLEY, N. R.. Magnetothermopower in Nd[sub 1−x]Eu[sub x]NiO[sub 3] compounds. Journal of Applied Physics, v. 101, n. 9, p. 09N509, 2007.
Texto completo (DOI)
We have measured magnetization M (T,H), thermal conductivity κ (T,H), and thermopower S (T,H) of polycrystalline samples of Nd1-x Eux Ni O3, 0≤x≤0.35, as a function of temperature and external magnetic field. The data indicate a metal-insulator (MI) transition in a wide range of temperature (200< TMI <325 K). The magnetic susceptibility (T) data, after the subtraction of the rare-earth contribution, exhibit a Curie-Weiss-like behavior at temperatures above TMI. Although a clear antiferromagnetic AF transition of the Ni sublattice is observed at TN ≤ TMI, (T) still increases down to 5 K, suggesting a heterogeneous ground state. The thermal conductivity of the NdNi O3 compound is not affected by an external magnetic field of 90 kOe in a wide range of temperature, and its temperature dependence below 15 K is approximately quadratic, strongly suggesting the presence of disorder. S (T) is negative above TMI and varies linearly with temperature. Below TMI, there is a minimum close to 120 K, and S (T) changes its sign at T∼30 K, indicating a competition between two types of charge carriers. A pronounced peak in S (T) at TS ∼20 K is observed and the peak remains unaltered under magnetic fields up to 90 kOe. However, its magnitude is enhanced by ∼25% with applied magnetic field, exhibiting a clear magnetothermopower effect. The combined results indicate a coexistence of ordered and disordered phases below TN and that an applied magnetic field is suitable for enhancing the thermoelectric properties close to TS. © 2007 American Institute of Physics.