Raman Spectroscopy

This Master’s dissertation project, conducted at UGC-DAE Consortium for Scientific Research, Indore, India, marked my entry into experimental condensed matter physics and materials science research.

Research Objectives

The project aimed to investigate spin-phonon coupling in rare-earth perovskite oxides (LaFeO₃ and LaMnO₃) by probing temperature-dependent vibrational modes across magnetic phase transitions. Understanding spin-lattice interactions is crucial for designing multiferroic materials with coupled magnetic and ferroelectric properties.

Methodology

I synthesized polycrystalline LaFeO₃ and LaMnO₃ using conventional solid-state reaction methods, followed by comprehensive characterization:

• Structural Analysis: X-ray diffraction (XRD) to determine crystal structure, lattice parameters, and phase purity
• Temperature-Dependent Raman Spectroscopy: Variable-temperature measurements (77 K to 773 K) to track phonon mode evolution across the Néel temperature (antiferromagnetic ordering)
• Spin-Phonon Coupling Analysis: Observing anomalous phonon frequency shifts and linewidth broadening near magnetic transition temperatures

Key Findings

The Raman spectra revealed distinct phonon mode behavior across the magnetic ordering temperature, indicating coupling between magnetic spins and lattice vibrations. Temperature-dependent frequency shifts and intensity variations of specific Raman modes provided evidence for spin-phonon interactions, consistent with theoretical predictions for perovskite antiferromagnets.

Skills Demonstrated

Solid-state synthesis, powder XRD, low/high-temperature Raman spectroscopy, crystal structure determination, phonon mode assignment, spin-phonon coupling analysis, data interpretation in strongly correlated oxide systems