Metallic states in Pb$_{10}$(PO$_4$)$_6$O induced by the Cu/O-insertions and carrier doping

TL;DR

This study uses density functional theory to show that Cu and O insertions in Pb-apatite induce metallic states with one-dimensional conduction along Cu-O chains, revealing potential mechanisms for superconductivity.

Contribution

The paper demonstrates that Cu and O insertions stabilize metallic states in Pb-apatite, highlighting the role of 1D Cu-O chains and carrier doping in inducing conductivity and magnetic changes.

Findings

Cu insertion stabilizes metallic states in Pb-apatite.

Conductance along the c-axis exceeds in-plane conductance by 2 orders of magnitude.

O insertion induces metallic states with higher out-of-plane conductance.

Abstract

The reports of room-temperature superconductivity in Cu-doped Pb-apatite draw intense interests and debates. Herein, based on the density functional theory, we show that the Cu-insertion in Pb-apatite is thermodynamically stable and further carrier doping can convert the system CuPb$_{10}$(PO$_4$)$_6$O into metal. The electric conduction is mainly along the one-dimensional (1D) Cu-O chains in the c-axis (out-of-plane). The calculated conductance along the c-axis is larger than the in-plane ones by 2 magnitude orders, indicating the 1D conduction behavior. Moreover, the 1D Cu-O chain is an anti-ferromagnetic Mott insulator at zero-doping point due to the super-exchange. Further electron/hole-doping will erase the anti-ferromagnetism. Therefore, the Cu-inserted system CuPb$_{10}$(PO$_4$)$_6$O show transport and magnetic features similar to the cuprate superconductors. On the other hand, the O-insertion can also induce the metallic states, in which the conductance along the out-of-plane direction is higher than the in-plane direction by 6-folds. Our results display the metallization of Pb$_{10}$(PO$_4$)$_6$O via Cu/O-insertions, and suggesting the electric conductions along the c-axis might dominate the transport behaviors.