We present results of transport measurements on superconducting Nb films with diluted triangular arrays (honeycomb and kagomé) of holes. The patterned films have large disk-shaped interstitial regions even when the edge-to-edge separations between nearest neighboring holes are comparable to the coherence length. Changes in the field interval of two consecutive minima in the field dependent resistance R(H) curves are observed. In the low field region, fine structures in the R(H) and T(c)(H) curves are identified in both arrays. Comparison of experimental data with calculation results reveals that these structures observed in honeycomb and kagomé hole arrays resemble those in wire networks with triangular and T(3) symmetries, respectively. The findings suggest that even in these specified periodic hole arrays with very large interstitial regions, the low field fine structures are determined by the connectivity of the nanostructures.
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http://dx.doi.org/10.1088/0953-8984/24/15/155702 | DOI Listing |
Commun Mater
January 2025
Physik-Institut, Universität Zürich, Zürich, Switzerland.
The discovery of unconventional superconductivity often triggers significant interest in associated electronic and structural symmetry breaking phenomena. For the infinite-layer nickelates, structural allotropes are investigated intensively. Here, using high-energy grazing-incidence x-ray diffraction, we demonstrate how in-situ temperature annealing of the infinite-layer nickelate PrNiO ( ≈ 0) induces a giant superlattice structure.
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January 2025
Materials Science Division, Argonne National Laboratory, Lemont, IL 60439, USA.
We report the appearance of superconductivity in single-unit-cell NdNiO, exhibiting a transition temperature similar to that of thicker films. In situ synchrotron x-ray scattering performed during growth of the parent phase, NdNiO, shows that the necessary layer-by-layer deposition sequence does not follow the sequence of the formula unit but an alternate order due to the relative stability of the perovskite unit cell. We exploit this insight to grow ultrathin NdNiO heterostructures and conduct in situ studies of topotactic reduction, finding that formation of the square-planar phase occurs rapidly and is highly sensitive to reduction temperature, with small deviations from the optimum condition leading to inhomogeneity and the loss of superconductivity.
View Article and Find Full Text PDFNat Commun
December 2024
School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, Nanjing, China.
Ferroelectric films are highly sought-after in micro-electro-mechanical systems, particularly with the trend towards miniaturization. However, their tendency to depolarize and degradation in piezoelectric properties when exposed to packaging procedures at temperatures exceeding 260 °C remains a significant challenge. Here, we reveal the prerequisites for self-poling and leverage these insights to achieve unprecedented macroscopic performance through a two-step approach involving texture construction and hierarchical heterogeneity engineering.
View Article and Find Full Text PDFAdv Mater
December 2024
Institute for Superconducting and Electronic Materials, Faculty of Engineering and Information Sciences, University of Wollongong, Innovation Campus, North Wollongong, NSW, 2500, Australia.
Piezoelectric micromachined ultrasound transducers (pMUTs), especially those using lead-free materials, are crucial next-generation microdevices for precise actuation and sensing, driving advancements in medical, industrial, and environmental applications. Bismuth ferrite (BiFeO) is emerging as a promising lead-free piezoelectric material to replace Pb(Zr,Ti)O in pMUTs. Despite its potential, the integration of BiFeO thin films into pMUTs has been hindered by poling issues.
View Article and Find Full Text PDFNature
December 2024
Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA.
Recently, the bilayer nickelate LaNiO has been discovered as a new superconductor with transition temperature T near 80 K under high pressure. Despite extensive theoretical and experimental work to understand the nature of its superconductivity, the requirement of extreme pressure restricts the use of many experimental probes and limits its application potential. Here, we present signatures of superconductivity in LaNiO thin films at ambient pressure, facilitated by the application of epitaxial compressive strain.
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