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arXiv · 1312.7058

Temperature dependent magnetic, dielectric and Raman studies of partially disordered La2NiMnO6

Pradeep Kumar·S. Ghara·B. Rajeswaran·D. V. S. Muthu·A. Sundaresan·A. K. Sood
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Abstract

We report a detailed magnetic, dielectric and Raman studies on partially disordered and biphasic double perovskite La2NiMnO6. DC and AC magnetic susceptibility measurements show two magnetic anomalies at TC1 ~ 270 K and TC2 ~ 240 K, which may indicate the ferromagnetic ordering of the monoclinic and rhombohedral phases, respectively. A broad peak at a lower temperature (Tsg ~ 70 K) is also observed indicating a spin-glass transition due to partial anti-site disorder of Ni2+ and Mn4+ ions. Unlike the pure monoclinic phase, the biphasic compound exhibits a broad but a clear dielectric anomaly around 270 K which is a signature of magneto-dielectric effect. Temperature-dependent Raman studies between the temperature range 12 K to 300 K in a wide spectral range from 220 cm-1 to 1530 cm-1 reveal a strong renormalization of the first as well as second-order Raman modes associated with the (Ni/Mn)O6 octahedra near TC1 implying a strong spin-phonon coupling. In addition, an anomaly is seen in the vicinity of spin-glass transition temperature in the temperature dependence of the frequency of the anti-symmetric stretching vibration of the octahedra.

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Pradeep Kumar, S. Ghara, B. Rajeswaran, D. V. S. Muthu, A. Sundaresan, A. K. Sood. 2013-12-26. Temperature dependent magnetic, dielectric and Raman studies of partially disordered La2NiMnO6. https://doi.org/10.1016/j.ssc.2014.01.002

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