Year: 2026
Type: article
Abstract: Exploiting electronic singularities to drive emergent quantum phenomena is a key basis in condensed matter physics, yet this powerful strategy has been largely limited to two dimensions, leaving the potential of three-dimensional materials often inaccessible. A “saddle-loop” singularity—a one-dimensional ring of saddle points—has been proposed as a way to extend the concept of van Hove singularities to three-dimensional electron systems, but has remained experimentally elusive. Here, we provide the direct experimental evidence for the saddle‑loop singularity in Pt(Bi 1− x Se x ) 2 , using angle‑resolved photoemission spectroscopy. We also show that the saddle loop is positioned closer to the Fermi level at low x values where the superconducting critical temperature is higher. Furthermore, our advanced theoretical calculations reveal that the saddle loop originates from inter-orbital hybridization, establishing a generalizable design concept. Our findings demonstrate a viable mechanism for realizing singular electronic states in three-dimensional electron systems, providing a platform to investigate correlation-driven phenomena in three dimensions.
Source: npj Quantum Materials
Authors: Y. Morita, K. Nakayama, N. Ito, T. Kato, T. Nakamura, H. Zhang, X. Tang, T. Lin, K. Yanagizawa, S. Souma, S. Masaki, T. Ikushima, Y. Moriyasu, K. Hagiwara, F. Matsui, K. Tanaka, K. Ozawa, D. Shiga, H. Kumigashira, M. Maeda, Y. Niimi, T. Kida, M. Hagiwara, T. K. Kim, C. Cacho, T. Takahashi, Y. Okada, S. Zhou, T. Koretsune, K. Kudo, T. Sato
Institutions: Tohoku University, Toyota Central Research and Development Laboratories (Japan), Institute for Materials Research, Tohoku University, Okinawa Institute of Science and Technology Graduate University, State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, The University of Osaka, Institute for Molecular Science, The Graduate University for Advanced Studies, SOKENDAI, High Energy Accelerator Research Organization, Institute of Materials Structure Science, Diamond Light Source
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $2,890
Awards: G1001434161, G2420621635, G3375220384, 有効模型データベースを用いた機能性物質の探索と設計, G3688360695, 三角形・ハニカム・カゴメネットワークにおける新奇超伝導状態の探索, Search for exotic quasiparticles by angle-resolved photoemission spectroscopy, G4892538354, G5338727572, G6891105196, G7521748366, 超高分解能マイクロARPESによるカゴメ超伝導体の電子状態イメージング, G7696577746, G8816044185, 化学結合の形成・切断の揺らぎを利用した新規高温超伝導体の創成
OpenAlex ID: W7165873012
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