Polaronic state and nanometer-scale phase separation in colossal magnetoresistive manganites

TL;DR

This study uses high-resolution scanning tunneling microscopy to observe polaronic states and nanometer-scale phase separation in manganites, revealing inhomogeneous metallic patches near the transition.

Contribution

It provides direct imaging evidence of polarons and phase separation at nanometer scales in manganites, advancing understanding of their electronic states.

Findings

Observation of stripe-like polaronic patterns in insulating state

Detection of nanometer-scale metallic clusters near transition

Confirmation of homogeneous ferromagnetic state

Abstract

High resolution topographic images obtained by scanning tunneling microscope in the insulating state of Pr0.68Pb0.32MnO3 single crystals showed regular stripe-like or zigzag patterns on a width scale of 0.4 - 0.5 nm confirming a high temperature polaronic state. Spectroscopic studies revealed inhomogeneous maps of zero-bias conductance with small patches of metallic clusters on length scale of 2 - 3 nm only within a narrow temperature range close to the metal-insulator transition. The results give a direct observation of polarons in the insulating state, phase separation of nanometer-scale metallic clusters in the paramagnetic metallic state, and a homogeneous ferromagnetic state.