Scaling of THz-conductivity at metal-insulator transition in doped manganites

TL;DR

This study investigates the THz conductivity and permittivity in doped manganites near the metal-insulator transition, revealing universal scaling laws and emphasizing the role of ac-conductivity and phononic energy scales.

Contribution

It uncovers universal scaling relationships in THz conductivity and permittivity across different manganite compounds near the MIT, highlighting the significance of ac-conductivity and phononic energy scales.

Findings

Universal scaling between permittivity and conductivity observed.

Scaling relationships hold across different doping levels.

Proportionality suggests importance of ac-conductivity and phononic energy scales.

Abstract

Magnetic field and temperature dependence of the Terahertz conductivity and permittivity of the colossal magnetoresistance manganite Pr_{0.65}Ca_{0.28}Sr_{0.07}MnO_3 (PCSMO) is investigated approaching the metal-to-insulator transition (MIT) from the insulating side. In the charge-ordered state of PCSMO both conductivity and dielectric permittivity increase as function of magnetic field and temperature. Universal scaling relationships between the changes in permittivity and conductivity are observed in a broad range of temperatures and magnetic fields. Similar scaling is also seen in La_{1-x}Sr_xMnO_3 for different doping levels. The observed proportionality points towards the importance of pure ac-conductivity and phononic energy scale at MIT in manganites.