Geometric frustration emerges when local interaction energies in an ordered lattice structure cannot be simultaneously minimized, resulting in a large number of degenerate states. The numerous degenerate configurations may lead to practical applications in microelectronics, such as data storage, memory and logic. However, it is difficult to achieve very high degeneracy, especially in a two-dimensional system. Here, we showcase in situ controllable geometric frustration with high degeneracy in a two-dimensional flux-quantum system. We create this in a superconducting thin film placed underneath a reconfigurable artificial-spin-ice structure. The tunable magnetic charges in the artificial-spin-ice strongly interact with the flux quanta in the superconductor, enabling switching between frustrated and crystallized flux quanta states. The different states have measurable effects on the superconducting critical current profile, which can be reconfigured by precise selection of the spin-ice magnetic state through the application of an external magnetic field. We demonstrate the applicability of these effects by realizing a reprogrammable flux quanta diode. The tailoring of the energy landscape of interacting 'particles' using artificial-spin-ices provides a new paradigm for the design of geometric frustration, which could illuminate a path to control new functionalities in other material systems, such as magnetic skyrmions, electrons and holes in two-dimensional materials, and topological insulators, as well as colloids in soft materials.
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http://dx.doi.org/10.1038/s41565-018-0162-7 | DOI Listing |
J Chem Theory Comput
January 2025
Department of Chemistry, Rice University, Houston, Texas 77005-1892, United States.
Generalized Hartree-Fock (GHF) is a long-established electronic structure method that can lower the energy (compared to spin-restricted variants) by breaking physical wave function symmetries, namely and . After an exposition of GHF theory, we assess the use of GHF trial wave functions in phaseless auxiliary field quantum Monte Carlo (ph-AFQMC-G) calculations of strongly correlated molecular systems including symmetrically stretched hydrogen rings, carbon dioxide, and dioxygen. Imaginary time propagation is able to restore symmetry and yields energies of comparable or better accuracy than CCSD(T) with unrestricted HF and GHF references, and consistently smooth dissociation curves─a remarkable result given the relative scalability of ph-AFQMC-G to larger system sizes.
View Article and Find Full Text PDFChemistry
January 2025
Indian Institute of Science Education and Research (IISER), Chemistry, Dr. Homi Bhabha Road, Pashan, 411008, Pune, INDIA.
Metal-organic frameworks (MOFs) are a fascinating class of structured materials with diverse functionality originating from the distinctive physicochemical properties. This review focuses on the specific chemical design of geometrically frustrated MOFs along with the origin of the intriguing magnetic properties. We have discussed the arrangement of spin centres (metal and ligand) which are responsible for the unusual magnetic phenomena in MOFs.
View Article and Find Full Text PDFAdv Mater
January 2025
Liquid Crystals and Photonics Group, Department of Electronics and Information Systems, Ghent University, Technologiepark-Zwijnaarde 126, Ghent, 9052, Belgium.
In liquid crystal (LC) cells, the surface patterning directs the self-assembly of the uniaxial building blocks in the bulk, enabling the design of stimuli-response optical devices with various functionalities. The combination of different anchoring patterns at both substrates can lead to surface induced frustration, preventing a purely planar and defect-free configuration. In cells with crossed assembly of rotating anchoring patterns, elastic deformations allow to obtain a defect-free bulk configuration, but an electrical stimulus can induce disclination lines.
View Article and Find Full Text PDFNano Lett
January 2025
Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, United States.
Pyrochlore materials are known for their exotic magnetic and topological phases arising from complex interactions among electron correlations, band topology, and geometric frustration. Interfaces between different pyrochlore crystals characterized by complex many-body ground states hold immense potential for novel interfacial phenomena due to the strong interactions between these phases. However, the realization of such interfaces has been severely hindered by limitations in material synthesis methods.
View Article and Find Full Text PDFNat Commun
December 2024
Department of Physics and Astronomy, Purdue University, West Lafayette, IN, USA.
Geometric frustration in two-dimensional Ising models allows for a wealth of exotic universal behavior, both Ising and non-Ising, in the presence of quantum fluctuations. In particular, the triangular antiferromagnet and Villain model in a transverse field can be understood through distinct XY pseudospins, but have qualitatively similar phase diagrams including a quantum phase transition in the (2+1)-dimensional XY universality class. While the quantum dynamics of modestly-sized systems can be simulated classically using tensor-based methods, these methods become infeasible for larger lattices.
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