Strain induced metal-insulator transition of magnetic SrRuO3 single layer in SrRuO3/SrTiO3 superlattice

Abstract

Ferromagnetic phase in a two-dimensional system plays an important role not only in applications but also in studies of phase transition theory. Among numerous ferromagnetic materials, SrRuO3 is famous for its half-metallicity, itinerant ferromagnetism and non-Fermi liquid metalicity. Single layer SrRuO3 in SrRuO3/SrTiO3 (SRO/STO) superlattice has been predicted as a two-dimensional half-metallic ferromagnetic system based on density functional theory (DFT). However, experiments show that metal-insulator transition associated with ferro-antiferromagnetism (FM-AFM) transition occurs when the thickness of SRO is less than 4 u.c. Combining DFT calculations with Monte Carlo simulations, we demonstrate in this work that the bulk ferromagnetic metallicity can be realized in single layer SRO in SRO/STO superlattice by manipulating the strain effect to trigger the metal-insulator transition, achieving two-dimensional (2D) half-metallic SRO thin film beyond the experimental observation of AFM insulator.Our results pave a new route to fulfill the ultrathin spin-polarized-2D electron gas (SP-2DEG).