Suppression of the two-dimensional electron gas in LaGaO3/SrTiO3 by cation intermixing

A Novel Method for Calculation of Molecular Energies and Charge Distributions by Thermodynamic Formalization

The paper describes a new approach to the thermodynamic formalization for calculation of molecular energy and charge distribution in ground state by means of the variational equation of DFT. In order to thermodynamically formalize the molecular calculation, the pseudo chemical potential (PCP) is conceptualized, where a molecule is broken into multi-phase(atom) one-component(electron) systems and the energy of system is represented as PCP. Calculation of the molecular energy and atomic charge by PCP is put forward, thereafter the approach is proved to be valid and its efficiency (accuracy and calculation speed) is verified.

Tunable magnetic and half-metallic properties of the two-dimensional electron gas in LaAlO3/SrTiO3(111) heterostructures

Half-metallic materials have gained a lot of attention because of their unique properties and applications in spintronic devices. Despite the fact that these materials have been studied by several research groups there are very limited studies on their heterostructure (HS) systems. In the current study we have investigated the electronic and magnetic properties of (LaAlO3)6.5/(SrTiO3)2.5(111) HS using density functional theory (DFT) calculations. We demonstrate that the system exhibits a 100% spin-polarized two-dimensional electron gas (2DEG) which is extremely confined to the Ti 3d orbitals of the SrTiO3 layers. In particular, this system can keep its half-metallic properties under different in-plane strains from -3 to 2%. This property proves that this material has relatively stable half-metallic properties. In addition, the conducting and magnetic ground states of the system can also be tailored by changing in-plane strain and interfacial cation intermixing of La and Sr (Sr ⇔ La intermixing). By increasing the in-plane lattice parameters, this system has the ability to evolve from a nonmagnetic to a ferromagnetic metal and then to a half-metal and by further increasing the in-plane lattice parameter it becomes a ferromagnetic insulator. Sr ⇔ La intermixing can destroy the original half-metallic properties and the system exhibits an AFM Mott-type insulator phase. Our results demonstrate that the system has high potential for application in the field of spintronics, and opens the prospect of using LaAlO3/SrTiO3(111) HSs to explore quantum phase transitions.

Interfacial defects induced electronic property transformation at perovskite SrVO3/SrTiO3 and LaCrO3/SrTiO3 heterointerfaces

Unravelling the atomic structure and chemical species of interfacial defects is critical to understanding the origin of interfacial properties in many heterojunctions.

Effects of surface defects on two-dimensional electron gas at NdAlO3/SrTiO3 interface

Density functional theory calculations of NdAlO₃/SrTiO₃ heterostructure show that two-dimensional electron gas (2-DEG) is produced at the interface with a built-in potential of ~0.3 eV per unit cell. The effects of surface defects on the phase stability and electric field of 2-DEG have been investigated. It is found that oxygen vacancy is easily to form on the NdAlO₃(001) surface, with a low threshold displacement energy and a low formation energy. This point defect results in surface reconstruction and the formation of a zigzag -Al-O-Al- chain, which quenches the built-in potential and enhances the carrier density significantly. These results will provide fundamental insights into understanding how surface defects influence the electronic behavior of 2-DEG and tuning their electronic properties through surface modification.