Unconventional critical magnetic behavior in the Griffiths ferromagnet La0.4Ca0.6MnO2.8 square(0.2) oxide

作者：Triki M^*; Dhahri E; Hlil E K

来源：Journal of Solid State Chemistry, 2013, 201: 63-67.

DOI：10.1016/j.jssc.2013.02.019

• Manganites
• Griffiths phase
• Phase transition
• Critical behavior

The effects of oxygen vacancy on the critical magnetic behavior in La0.4Ca0.6MnO2.8 square(0.2) around the paramagnetic-ferromagnetic (PM-FM) phase transition were investigated through various techniques such as modified Arrott plot, Kouvel-Fisher method and critical isotherm analysis via dc magnetization measurements recorded around the Curie temperature T-C. The obtained critical exponents values are beta similar to 0.8, gamma similar to 0.7 and delta similar to 1.882 with T-C similar to 164.5 K. Thus the scaling law gamma+beta=delta beta is fulfilled. The critical exponents obey the single scaling-equation of state M(H,epsilon)vertical bar epsilon vertical bar(-beta) = f(+/-)(H vertical bar epsilon vertical bar(-(beta+gamma))) where, f(+) for T > T-C and f(-) for T > T-C. The found exponents are inconsistent with any known universality class. These results attributed to the existence of Griffiths Phase (Triki et al. (2012) [1]) seem to actually reflect the unconventional critical scaling of the magnetic susceptibility.

• 出版日期2013-5