Epitaxial Growth of Fe/MgO/Fe Heterostructures on SrTiO₃(001) Substrates by Magnetron Sputtering

Abstract

We report on the preparation and structural properties of MgO/Fe bilayers (a MgO thin film on an Fe thin film), Fe/MgO bilayers (an Fe thin film on a MgO thin film), and Fe/MgO/Fe trilayers, all grown by magnetron sputtering on SrTiO3(001) substrates. We investigated the structural properties of these heterostructures with X-ray diffraction (XRD) (θ–2 θ scan, rocking curve and pole figure measurements), atomic force microscopy (AFM), and high-resolution transmission electron microscopy (HRTEM). Single-crystalline epitaxial growth was confirmed by the X-ray pole figure measurements for both the MgO/Fe and Fe/MgO bilayers, which were the basic layer components for the Fe/MgO/Fe trilayer. The cross-sectional HRTEM clearly indicated epitaxial growth of the Fe/MgO/Fe trilayer structures on the SrTiO3(001) substrates with excellent flat interfaces having roughness of less than a few angstroms.

In situsmall-angle x-ray and nuclear resonant scattering study of the evolution of structural and magnetic properties of an Fe thin film on MgO (001)

“…This treatment is known to improve surface quality and reduce carbon contamination, and such surfaces have been used in the literature to deposit good quality films [28][29][30]. Fe film on such substrate was deposited using the technique of magnetron sputtering, which has been used quite often in the literature to deposit TMR multilayers [31,32]. Growth behavior of the film was studied in situ using GISAXS and GINRS measurements.…”

Artificial neuron operations and spike-timing-dependent plasticity using memristive devices for brain-inspired computing

“…The stacking structure of these devices is unlike that of the single crystalline systems in metal-oxide tunnel devices, which are single MgO tunnel barrier devices. [20][21][22][23] A selfcompliant and self-rectifying resistive switching memory cell, with area-scalable switching currents and featuring high on-state nonlinearity and low reset current density, has been reported. 24) Even if the switching stack is tuned in accordance with memory requirements, the cell does not exhibit analoglike switching behavior.…”

The fluctuated structural/electronic properties of SrTiO3 two-dimensional materials caused by surface effects

“…The STO (001) surface is renowned for its high flatness and ordered atomic arrangement, making it particularly suitable for producing high-quality thin films and interface materials [24]. It exhibits excellent compatibility with the lattices of many other materials and can form special interfaces, which makes the surface of STO (001) often used as a template film for growing heterostructures [25,26]. However, due to the loose atomic arrangement, the surface of STO (110) has relatively more structural defects and surface reactivity, which makes these characteristics advantageous in specific applications [27].…”