Unconventional Phase Transition

The goal of this project is to understand, design and discover novel functional materials exhibiting metal-insulator transitions (MITs) for highly tunable electronic materials platform.  This project will establish the structure-property relationships, i.e. the genetic code embodied in atomic-scale structure, e.g.  bond angles, bond lengths, and polyhedral connectivity, that predisposes a specific electronic state (metallic or insulating) in transition-metal oxides (TMOs).

Approach

  • We perform density functional theory (DFT) simulations to study the crystal and electronic structures of transition metal oxides that exhibit MITs. Properties of interest typically include lattice constants, electronic structures (band structures, density of states, dielectric constants), lattice dynamics (phonon dispersions), thermodynamic properties. We will utilize the link between these features and the macroscopic response to realize new MIT materials.
  • Model Hamiltonian of candidate compounds are constructed based on tight-binding model or extended Huckel thoery. We expect to obtain some insights on the effect of structural perturbation on electronic structures, e.g. orbital ordering and degeneracy.
  • High-throughput screening method will be implemented based on experimental/theoretical simulation database and our understanding of the key features associated with MIT behavior. New compounds exhibiting MITs can be discovered by this method from existing materials database, and we will do further investigation on them to complete our MIT materials database.

Selected Publications

Electronic properties of bulk and thin film SrRuO3: Search for the metal-insulator transition, J. M. Rondinelli, N. M. Caffrey, S. Sanvito, N. A. Spaldin, Phys. Rev. B 78, 155107 (2008). DOI: 10.1103/PhysRevB.78.155107

Tunable metal-insulator transition, Rashba effect and Weyl Fermions in a relativistic charge-ordered ferroelectric oxide, J. He, D. D. Sante, R. Li, X. Q. Chen, J. M. Rondinelli, C. Franchini, Nat. Commun. 9, 492 (2018). DOI: 10.1038/s41467-017-02814-4