Publications by authors named "Kook Tae Kim"
Phase-field simulations were performed on the polar vortex array structure appearing in the SrTiO/PbTiO/SrTiO heterostructure to investigate the Kittel law relationship (w ∝ d) between the vortex array period (w) and the PbTiO ferroelectric layer thickness (d). Quasi-two-dimensional simulation results show that the equilibrium period can be determined from the relationship between the size of the simulation box and the total free energy density and that the obtained period obeys the Kittel law. However, three-dimensional simulation results show that the polar vortex arrays are not homogeneous in the direction perpendicular to the vortex plane.
View Article and Find Full Text PDFInterfacial magnetic interactions between different elements are the origin of various spin-transport phenomena in multi-elemental magnetic systems. We investigate the coupling between the magnetic moments of the rare-earth, transition-metal, and heavy-metal elements across the interface in a GdFeCo/Pt thin film, an archetype system to investigate ferrimagnetic spintronics. The Pt magnetic moments induced by the antiferromagnetically aligned FeCo and Gd moments are measured using element-resolved x-ray measurements.
View Article and Find Full Text PDFStructural Chirality of Polar Skyrmions Probed by Resonant Elastic X-Ray Scattering.
Phys Rev Lett
December 2022
Article Synopsis
- The study addresses the challenges in characterizing small nanostructures, specifically ferroelectric and ferromagnetic skyrmions, due to their complex three-dimensional structures.
- Resonant elastic x-ray scattering (REXS) has been identified as a promising technique for investigating these nanostructures, particularly for studying the chirality of spin textures.
- The research introduces a modeling framework for applying REXS to charge quadrupole moments in ferroelectrics, demonstrating its effectiveness in analyzing the coexistence and structure of polar skyrmions with mixed chirality.
Article Synopsis
- Resonant elastic X-ray scattering (REXS) is a powerful technique that combines the spatial resolution of diffraction with electronic information, enabling detailed studies of solid-state systems and their magnetic, charge, spin, and orbital properties.
- A new application of REXS focuses on understanding the chiral structure of electric polarization in ferroelectric oxide superlattices, specifically analyzing the polarization vectors through an anisotropic tensor related to the quadrupole moment.
- The authors present a thorough theoretical framework to interpret experimental results from Ti L-edge REXS of a polar vortex array in a PbTiO/SrTiO superlattice, suggesting that REXS can be a valuable tool for exploring both electric and magnetic properties of ch