First principles electron transport in magnetoelectric SrRuO₃/BaTiO₃/SrTiO₃/SrRuO₃interfaces

Area of Science:

• Condensed Matter Physics
• Materials Science
• Solid-State Chemistry

Background:

• All-oxide ferroelectric tunnel junctions (FTJs) based on perovskites like SrRuO3/BaTiO3/SrTiO3 are of interest for high-density, low-power applications.
• Their tunable transport properties and potential for atomic-scale device scaling make them attractive for next-generation electronics.

Purpose of the Study:

• To investigate the electronic structure and tunneling transport properties of magnetoelectric SrRuO3/BaTiO3/mSrTiO3/SrRuO3 interfaces.
• To explore the influence of RuO6 octahedra tilts and magnetic SrRuO3 electrodes on device characteristics.

Main Methods:

• First-principles calculations.
• Non-equilibrium Green's functions (NEGF) formalism.

Main Results:

• Band alignment predicts polarization-dependent Schottky or Ohmic contacts for m(STO)=0, and only Schottky contacts for m(STO)=2 and 4.
• Tunnel electroresistance (TER) and tunnel magnetoresistance (TMR) ratios were evaluated at 0 K and 300 K.
• The m(STO)=2 heterostructure exhibits the most significant magnetoelectric response, with co-existing giant TER and TMR effects.
• Interfacial magnetoelectric coupling is insufficient to control TMR via polarization switching, despite strong SrRuO3 ferromagnetism.

Conclusions:

• The SrRuO3/BaTiO3/mSrTiO3 system demonstrates significant magnetoelectric coupling and tunable transport properties.
• The m(STO)=2 interface is particularly promising for applications requiring simultaneous electroresistance and magnetoresistance effects.
• Further research may be needed to enhance interfacial magnetoelectric coupling for polarization-controlled magnetoresistance.