# Cubic lead perovskite PbMoO3 with anomalous metallic behavior

## TL;DR

This study reports the synthesis of a new cubic Pb-based perovskite, PbMoO$_3$, which exhibits anomalous metallic behavior and unusual thermal and electrical properties linked to low-energy vibrational modes and electron-phonon coupling.

## Contribution

The paper introduces a previously unreported cubic PbMoO$_3$ perovskite with unique metallic and vibrational properties, expanding understanding of Pb-based perovskites.

## Key findings

- PbMoO$_3$ crystallizes in a cubic structure at room temperature.
- Exhibits metallic behavior down to 0.1 K with linear resistivity dependence.
- Displays large low-temperature specific heat and anomalous thermal properties.

## Abstract

A previously unreported Pb-based perovskite PbMoO$_3$ is obtained by high-pressure and high-temperature synthesis. This material crystallizes in the $Pm\bar{3}m$ cubic structure at room temperature, making it distinct from typical Pb-based perovskite oxides with a structural distortion. PbMoO$_3$ exhibits a metallic behavior down to 0.1 K with an unusual $T$-sub linear dependence of the electrical resistivity. Moreover, a large specific heat is observed at low temperatures accompanied by a peak in $C_P/T^3$ around 10 K, in marked contrast to the isostructural metallic system SrMoO$_3$. These transport and thermal properties for PbMoO$_3$, taking into account anomalously large Pb atomic displacements detected through diffraction experiments, are attributed to a low-energy vibrational mode, associated with incoherent off-centering of lone pair Pb$^{2+}$ cations. We discuss the unusual behavior of the electrical resistivity in terms of a polaron-like conduction, mediated by the strong coupling between conduction electrons and optical phonons of the local low-energy vibrational mode.