MPI for Solid State Research: NbSe2 Exhibits First-Order Phase Transition to Pairing State

Researchers at the MPI for Solid State Research have observed that Matthieu Le Tacon presented research on a first-order phase transition into a pairing state within the material niobium diselenide (NbSe2), a finding that challenges conventional understanding of superconductivity in similar compounds. While most materials of this type undergo second-order transitions, this distinct behavior in NbSe2 suggests a potentially more robust or unusual mechanism. Simultaneously, Takeshi Kondo of the University of Tokyo is presenting research titled “Coherence and pairing enhancement in a trilayer cuprate with layer-selective charge order,” focusing on a novel approach to cuprate superconductivity through multilayer structures. Ding Zhang from Peking University is employing resonant x-ray reflectometry to analyze the layer-resolved electronic structure of LaNiO3 thin films, promising high-resolution insights into this complex material.

Cuprate and Nickelate Superconductivity Investigations

This unexpected behavior was highlighted during the Quantum Materials program, where researchers are actively probing the intricacies of both cuprate and nickelate superconductors. This investigation suggests that manipulating the arrangement of atomic layers and their associated charge distributions could unlock new pathways to enhanced superconductivity. This precise technique allows for a detailed mapping of electron behavior within each layer of the material, potentially revealing crucial insights into the origins of superconductivity in nickelates. The program also showcased investigations into the interplay between magnetic and electronic structures within these materials, as well as explorations of polymorphic crystal structures in nickelates. Researchers are employing a diverse toolkit, from time-resolved x-ray studies to Raman spectroscopy, to unravel the complex quantum phenomena governing these exotic states of matter and are actively seeking to understand how these materials deviate from established theoretical models. These combined efforts promise a deeper understanding of high-temperature superconductivity and the potential for realizing these materials in future technologies.

Kagome Superconductors & Charge Density Wave Phenomena

Recent investigations are revealing surprising complexities within kagome superconductors, materials exhibiting unique geometric lattices and a propensity for charge density wave (CDW) formation. Matthieu Le Tacon presented research indicating that the pathway to superconductivity in NbSe2 may differ significantly from other known superconductors, demanding a reevaluation of existing theoretical models. Further complicating this picture is the exploration of multilayered cuprates; Takeshi Kondo presented research on “Coherence and pairing enhancement in a trilayer cuprate with layer-selective charge order,” indicating a shift towards understanding how interlayer interactions influence superconductivity and charge ordering. This approach could unlock new strategies for enhancing superconducting properties by precisely controlling the arrangement of atomic layers. Complementing these efforts, materials scientists are employing advanced techniques to probe the electronic structure of LaNiO3 thin films.

This high-resolution analysis promises to reveal subtle correlations between electronic structure and the emergence of charge density waves, potentially identifying key factors governing the superconducting transition in these complex materials. Christine Au-Yeung of UBC is probing density wave order in multilayered systems. The combined data from these diverse investigations is expected to refine our understanding of the interplay between CDW phenomena and superconductivity in these intriguing materials.

Quantum Magnetism in 2D Materials & Topological Systems

The investigation into cuprates is complemented by work exploring nickelates, with Christine Au-Yeung of UBC probing density wave order in multilayered systems. This observation is driving exploration into how manipulating material structure impacts superconductivity. The pursuit of understanding quantum magnetism extends to two-dimensional van der Waals magnets, where researchers like Kensuke Kobayashi of the University of Tokyo are investigating condensed matter physics. Simultaneously, theoretical work, such as that by Walter Metzner of the MPI for Solid State Research, is attempting to model the origins of the pseudogap from magnetic fluctuations in both the Hubbard model and cuprates, bridging the gap between theory and experimental observation and furthering the understanding of complex quantum systems.