Nonmagnetic SrTiO3 Research Articles

Exotic Magnetic Anisotropy Near Digitized Dimensional Mott Boundary.

The magnetic anisotropy of low-dimensional Mott systems exhibits unexpected magnetotransport behavior useful for spin-based quantum electronics. Yet, the anisotropy of natural materials is inherently determined by the crystal structure, highly limiting its engineering. The magnetic anisotropy modulation near a digitized dimensional Mott boundary in artificial superlattices composed of a correlated magnetic monolayer SrRuO3 and nonmagnetic SrTiO3 , is demonstrated. The magnetic anisotropy is initially engineered by modulating the interlayer coupling strength between the magnetic monolayers. Interestingly, when the interlayer coupling strength is maximized, a nearly degenerate state is realized, in which the anisotropic magnetotransport is strongly influenced by both the thermal and magnetic energy scales. The results offer a new digitized control for magnetic anisotropy in low-dimensional Mott systems, inspiring promising integration of Mottronics and spintronics.

Spontaneous positive exchange bias effect in SrFeO3−x/SrCoO3−x epitaxial bilayer

A novel phenomenon of spontaneous positive exchange bias (PEB) is reported in SrFeO3−x/SrCoO3−x epitaxial bilayer without undergoing any magnetic field treatment. When inserting a thick SrTiO3 (STO) nonmagnetic spacer (about 6 nm) into the bilayer interface, this phenomenon still exists. Based on a series of testing means, the spontaneous PEB effect is supposed to be mainly related to short-range ferromagnetic (FM) exchange coupling at the interface when there is no STO spacer. As the STO interlayer reaches up to a certain thickness, short-range coupling interaction basically disappears. At this time, the long-range dipole field may be responsible for the coupling of the FM and antiferromagnetic (AFM) layer across the nonmagnetic STO and then leads to the same bias effect. Our discoveries provide a new way to realize and manipulate spontaneous exchange bias-based spintronics devices, such as magnetic recording heads and spin valves.

Wedge-Shaped Potential and Airy-Function Electron Localization in Oxide Superlattices

Oxide superlattices and microstructures hold the promise for creating a new class of devices with unprecedented functionalities. Density-functional studies of the recently fabricated, lattice-matched perovskite titanates (SrTiO3)n/(LaTiO3)m reveal a classic wedge-shaped potential well for the monolayer (m = 1) structure, originating from the Coulomb potential of a two-dimensional charged La sheet. The potential in turn confines the electrons in the Airy-function-localized states. Magnetism is suppressed for the monolayer structure, while in structures with a thicker LaTiO3 part, bulk antiferromagnetism is recovered, with a narrow transition region separating the magnetic LaTiO3 and the nonmagnetic SrTiO3.