Ab initio Low-Energy Model of Transition-Metal-Oxide Heterostructure LaAlO3/SrTiO3

作者：Hirayama Motoaki^*; Miyake Takashi; Imada Masatoshi

来源：Journal of the Physical Society of Japan, 2012, 81(8): 084708.

DOI：10.1143/JPSJ.81.084708

• first-principles calculation
• effective Hamiltonian
• downfolding
• constrained RPA method
• correlated-electron systems
• heterostructure
• interface
• two-dimensional electron systems

We develop a multiscale ab initio scheme for correlated electrons (MACE) for transition-metal-oxide heterostructures, and determine the parameters of the low-energy effective model. By separating Ti t(2g) bands near the Fermi level from the global Kohn-Sham (KS) bands of LaAlO3 (LAO)/SrTiO3 (STO), which are highly entangled with each other, we are able to calculate the parameters of the low-energy effective model of the interface with the help of constrained random phase approximation (cRPA). The on-site energies of the Ti t(2g) orbitals in the 1st layer is about 650 meV lower than those in the second layer. In the 1st layer, the transfer integral of the Ti t(2g) orbital is nearly the same as that of bulk STO, while the effective screened Coulomb interaction becomes about 10% larger than that of bulk STO. The differences in the parameters from bulk STO decrease rapidly with increasing distance from the interface. Our present versatile method enables us to derive effective ab initio low-energy models and to study interfaces of strongly correlated electron systems from first principles.

• 出版日期2012-8