Low Temperature Dynamic Polaron Liquid in a Manganite Exhibiting Colossal Magnetoresistance

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Materials

Background:

• Polarons, formed by electrons and lattice distortions, are common in insulators.
• The evolution of polarons during transitions to metallic and superconducting states is not well understood.
• Understanding these transitions is crucial for developing novel quantum materials.

Purpose of the Study:

• To investigate the behavior of polarons across the metal-to-insulator transition in La_{1.2}Sr_{1.8}Mn_{2}O_{7}.
• To elucidate the changes in electron-lattice coupling during this transition.
• To identify the polaronic state in the metallic phase of this quantum material.

Main Methods:

• Utilized resonant inelastic x-ray scattering (RIXS) to probe electron-lattice interactions.
• Studied the colossal magneto-resistive bi-layer manganite La_{1.2}Sr_{1.8}Mn_{2}O_{7}.
• Analyzed spectral weight redistribution across the metal-to-insulator transition.

Main Results:

• In the insulating state, observed harmonic emissions of a dispersionless oxygen phonon.
• In the metallic state, detected a shift of spectral weight to a high-energy continuum.
• Demonstrated a transition from static to dynamic lattice distortions, forming a dynamic polaron liquid.

Conclusions:

• The metal-to-insulator transition involves a significant change in electron-lattice coupling dynamics.
• A novel dynamic polaron liquid ground state exists in the metallic phase of La_{1.2}Sr_{1.8}Mn_{2}O_{7}.
• These findings offer new insights into polaron behavior in quantum materials.