Using first-principles-based simulations merging an effective Hamiltonian scheme with scaling, symmetry, and topological arguments, we find that an overlooked Berezinskii-Kosterlitz-Thouless (BKT) phase sustained by quasicontinuous symmetry emerges between the ferroelectric phase and the paraelectric one of BaTiO_{3} ultrathin film, being under tensile strain. Not only do these results provide an extension of BKT physics to the field of ferroelectrics, but they also unveil their nontrivial critical behavior in low dimensions.
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http://dx.doi.org/10.1103/PhysRevLett.119.117601 | DOI Listing |
Phys Rev Lett
December 2024
School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA.
The crystallographic restriction theorem constrains two-dimensional nematicity to display either Ising (Z_{2}) or three-state-Potts (Z_{3}) critical behaviors, both of which are dominated by amplitude fluctuations. Here, we use group theory and microscopic modeling to show that this constraint is circumvented in a 30°-twisted hexagonal bilayer due to its emergent quasicrystalline symmetries. We find a critical phase dominated by phase fluctuations of a Z_{6} nematic order parameter and bounded by two Berezinskii-Kosterlitz-Thouless (BKT) transitions, which displays only quasi-long-range nematic order.
View Article and Find Full Text PDFNano Lett
January 2025
National Laboratory of Solid State Microstructures, Jiangsu Key Laboratory of Artificial Functional Materials, College of Engineering and Applied Sciences, Nanjing University, Nanjing 210023, P. R. China.
Transition metal oxide interfaces have garnered great attention due to their fascinating properties that are absent in their bulk counterparts. The high mobility and coexistence of superconductivity and magnetism at these interfaces remain compelling research topics. Here, we first report superconductivity in the 2DEG formed at the LaFeO/SrTiO interfaces, characterized by a superconducting transition temperature () of 333 mK and a superconducting layer thickness of 13.
View Article and Find Full Text PDFJ Phys Chem C Nanomater Interfaces
November 2024
Department of Inorganic Chemistry, Faculty of Chemical Technology, University of Chemistry and Technology Prague, Technická 5, 166 28 Prague 6, Czech Republic.
Phys Rev Lett
September 2024
International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China and Collaborative Innovation Center of Quantum Matter, 100871 Beijing, China.
Motivated by the experiments on the triangular lattice bilayer colbaltate K_{2}Co_{2}(SeO_{3})_{3}, we consider an extended XXZ model to explore the underlying physics. The model is composed of interacting Co^{2+} dimers on the triangular lattice, where the Co^{2+} ion provides an effective spin-1/2 local moment via the spin-orbit coupling and the crystal field effect. The intradimer interaction is dominant and would simply favor the local spin singlet, and the interdimer interactions compete with the interdimer interaction, leading to rich behaviors.
View Article and Find Full Text PDFPhys Rev Lett
September 2024
School of Physics, Beijing Institute of Technology, Beijing 100081, China.
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