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Heisenberg-like critical properties in ferromagnetic Nd1-xPbxMnO3 single crystals

Ghosh, N and Rossler, S and Rossler, UK and Nenkov, K and Elizabeth, Suja and Bhat, HL and Dorr, K and Muller, KH (2006) Heisenberg-like critical properties in ferromagnetic Nd1-xPbxMnO3 single crystals. In: Journal of Physics-Condensed Matter, 18 (2). pp. 557-567.

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Abstract

Static magnetization for single crystals of insulating Nd0.85Pb0.15MnO3 and marginally conducting Nd0.70Pb0.30MnO3 has been studied around the ferromagnetic to paramagnetic transition temperature T-C. Results of measurements carried out in the critical range vertical bar(T - T-C)/T-C vertical bar <= 0.1 are reported. Critical exponents beta and gamma for the thermal behaviour of magnetization and susceptibility have been obtained both by modified Arrott plots and the Kouvel-Fisher method. The exponent delta independently obtained from the critical isotherm was found to satisfy the Widom scaling relation delta = gamma/beta + 1. For both compositions the values of exponents are consistent with those expected for isotropic magnets belonging to the Heisenberg universality class with short-range exchange in three dimensions. Correspondingly, the specific heat displays only a cusp-like anomaly at the critical temperature of these crystals which is consistent with an exponent alpha < 0. The results show that the ferromagnetic ordering transition in Nd1-xPbxMnO3 in the composition range 0.15 <= x <= 0.40 is continuous. This mixed-valent manganite displays the conventional properties of a Heisenberg-like ferromagnet, irrespective of the differing transport properties and in spite of low ordering temperatures T-C = 109 and 147.2 K for x = 0.15 and 0.30, respectively.

Item Type: Journal Article
Additional Information: Copyright of this article belongs to Institute of Physics Publishing.
Department/Centre: Division of Physical & Mathematical Sciences > Physics
Date Deposited: 07 Sep 2010 04:53
Last Modified: 19 Sep 2010 06:15
URI: http://eprints.iisc.ernet.in/id/eprint/31862

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