Semimetallic transport properties of epitaxially stabilized perovskite CaIrO3 films

TL;DR

This study synthesizes epitaxial CaIrO3 films and investigates their transport properties, revealing semimetallic behavior with coexisting electrons and holes, and robustness against strain due to symmetry-protected Dirac points.

Contribution

It demonstrates the stabilization of perovskite CaIrO3 films and characterizes their semimetallic transport properties under different strain conditions.

Findings

CaIrO3 films are semimetallic with coexisting electrons and holes.

The semimetallic state is robust against tensile and compressive strains.

Presence of symmetry-protected Dirac points prevents insulating transition.

Abstract

We report on the synthesis and transport properties of perovskite (Pv) CaIrO3 thin films. The Pv phase of CaIrO3 was stabilized by epitaxial growth on SrTiO3, (LaAlO3)0.3(Sr2AlTaO6)0.7, and LaAlO3 substrates with strong tensile, weak tensile, and compressive strains, respectively. The resistivity of these films showed a poorly metallic behavior. The Hall resistivity exhibited a sign change as a function of temperature and a nonlinear magnetic-field dependence, which clearly indicated the coexistence of electrons and holes and hence supported that Pv CaIrO3 films are semimetallic. The observed robustness of the semimetallic ground state against tensile and compressive strains is consistent with the presence of symmetry-protected Dirac points (nodes) around the Fermi level that prohibits the system from becoming a band insulator.