Possible observation of Griffith phase over large temperature range in plasma sintered La0.^sub 67^Ca^sub 0.33^MnO^sub 3

• Published in: Journal of magnetism and magnetic materials Vol. 448; p. 287
• Main Authors: Mishra, DK, Roul, BK, Singh, SK, Srinivasu, VV
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier BV 15-02-2018
• Subjects: Clusters; Curie temperature; Electron paramagnetic resonance; Electron spin; Ferroelectrics; Ferromagnetic resonance; Ferromagnetism; Inhomogeneity; Microstructure; Phase transitions; Plasma sintering; Quenching; Rapid quenching (metallurgy); Spin resonance; Studies; Transition temperature
• ISSN: 0304-8853; 1873-4766

We report on the possible observation of Griffith phase in a wide range of temperature (>272-378 K) in the 2.5 min plasma sintered La0.67Ca0.33MnO3 (LCMO) as deduced from careful electron spin resonance studies. This is 106 K higher than the paramagnetic to ferromagnetic transition (Curie transition ~272 K) temperature. The indication of Griffith phase in such a wide range is not reported earlier by any group. We purposefully prepared LCMO samples by plasma sintering technique so as to create a disordered structure by rapid quenching which we believe, is the prime reason for the observation of Griffith Phase above the Curie transition temperature. The inverse susceptibility curve represents the existence of ferromagnetic cluster in paramagnetic region. The large resonance peak width (40-60 mT) within the temperature range 330-378 K confirms the sample magnetically inhomogeneity which is also established from our electron probe microstructure analysis (EPMA). EPMA establishes the presence of higher percentage of Mn3+ cluster in comparison to Mn4+. This is the reason for which Griffith state is enhanced largely to a higher range of temperature.