Critical properties of the double exchange ferromagnet Nd0.4Pb0.4MnO3

TL;DR

This study investigates the critical magnetic properties of Nd0.4Pb0.4MnO3, revealing that its critical exponents align with the 3D Heisenberg universality class, indicating short-range magnetic interactions.

Contribution

The paper provides detailed critical exponent measurements for Nd0.4Pb0.4MnO3, confirming its classification within the 3D Heisenberg ferromagnet universality class.

Findings

Critical temperature T_C = 156.47 K

Critical exponents beta, gamma, delta match 3D Heisenberg model

Scaling law gamma+beta=delta is satisfied

Abstract

Results of a study of dc-magnetization M(T, H), performed on a Nd0.6Pb0.4MnO3 single crystal in the temperature range around T_C (Curie temperature) which embraces the critical region | epsilon | = |T -T_C |/T_C <= 0.05 are reported. The magnetic data analyzed in the critical region using the Kouvel-Fisher method give the values for the T_C =156.47 +/- 0.06 K and the critical exponents, beta = 0.374 +/- 0.006 (from the temperature dependence of magnetization), and gamma = 1.329 +/- 0.003 (from the temperature dependence of initial susceptibility). The critical isotherm M(T_C, H) gives delta = 4.547 +/- 0.1. Thus the scaling law gamma+beta=delta beta is fulfilled. The critical exponents obey the single scaling-equation of state M(H, epsilon) = epsilon^b f_+/- (H/epsilon^(beta + gamma)) where, f_+ for T > T_C and f_- for T< T_C. The exponent values are very close to those expected for the universality class of 3D Heisenberg ferromagnets with short-range interactions.