Probing the Subtle Magnetic Transitions with Raman Spectroscopy in a Bi-layered La1.15Sr1.85Mn2O7 Single Crystal

The magnetic properties of a single crystalline bi-layered La1.15Sr1.85Mn2O7 manganite have been studied using magnetization measurements complemented by low-temperature Raman spectroscopy. The bulk magnetization measurements revealed a magnetic transition at a temperature of Tc = 85 K. The temperature dependence of the inverse magnetization data revealed an upward deviation from the Curie-Weiss law at a temperature of T* = 250 K, which is indicative of the onset of the short-ranged ferromagnetic metallic cluster formation based on the phase separation/coexistence models. Raman spectrum analysis of certain peaks revealed interesting phenomena at around T*. The T* that has been observed in the inverse magnetization data and the Raman spectrum analysis of certain peaks has been discussed. Our observations demonstrate that Raman spectroscopy is a powerful technique for the determination of subtle magnetic phenomena in this group of materials.