2023-12-11 チャルマース工科大学
◆研究においては、量子臨界点の存在が「奇妙な金属」と呼ばれる相と関連しており、これについての理論を強化する結果が得られた。X線散乱実験を通じて行われた研究では、電荷密度のゆらぎがカペートの電気抵抗に影響を与え、これを「奇妙」にする様子が明らかになった。
＜関連情報＞
- https://news.cision.com/chalmers/r/strange-metal-discovery-paves-way-for-sustainable-superconductors,c3891202
- https://www.nature.com/articles/s41467-023-42961-5
電荷密度ゆらぎによる銅酸化物の量子臨界のサイン Signature of quantum criticality in cuprates by charge density fluctuations
Riccardo Arpaia,Leonardo Martinelli,Marco Moretti Sala,Sergio Caprara,Abhishek Nag,Nicholas B. Brookes,Pietro Camisa,Qizhi Li,Qiang Gao,Xingjiang Zhou,Mirian Garcia-Fernandez,Ke-Jin Zhou,Enrico Schierle,Thilo Bauch,Ying Ying Peng,Carlo Di Castro,Marco Grilli,Floriana Lombardi,Lucio Braicovich & Giacomo Ghiringhelli
Nature Communications Published:08 November 2023
DOI:https://doi.org/10.1038/s41467-023-42961-5
Abstract
The universality of the strange metal phase in many quantum materials is often attributed to the presence of a quantum critical point (QCP), a zero-temperature phase transition ruled by quantum fluctuations. In cuprates, where superconductivity hinders direct QCP observation, indirect evidence comes from the identification of fluctuations compatible with the strange metal phase. Here we show that the recently discovered charge density fluctuations (CDF) possess the right properties to be associated to a quantum phase transition. Using resonant x-ray scattering, we studied the CDF in two families of cuprate superconductors across a wide doping range (up to p = 0.22). At p* ≈ 0.19, the putative QCP, the CDF intensity peaks, and the characteristic energy Δ is minimum, marking a wedge-shaped region in the phase diagram indicative of a quantum critical behavior, albeit with anomalies. These findings strengthen the role of charge order in explaining strange metal phenomenology and provide insights into high-temperature superconductivity.
