2023-11-23 ライス大学
◆Science誌に発表されたこの研究によれば、奇妙な金属を構成する電気は通常のキャリアではなく、キャリアが不確定であるか、または存在しない可能性があります。実験は奇妙な金属の特異な挙動を持つ量子臨界物質（YbRh2Si2）の微細なワイヤーで行われ、これにより電荷がどのように集団的に移動するかについての初めての直接の証拠が得られました。これは従来の金属とは異なる挙動で、量子重ね合わせが高度に絡み合っています。
◆研究者は、これが電荷が通常のキャリアではなく、より複雑な方法で移動する可能性があることを示唆しています。この結果は、物理学者たちが使用するキャリアの概念である準粒子が奇妙な金属で機能しない可能性を初めて実証するものであり、今後、他の奇妙な金属行動を示す物質にも同様の挙動が見られる可能性があるかもしれません。
＜関連情報＞
- https://news.rice.edu/news/2023/strange-metal-strangely-quiet-noise-experiment
- https://www.science.org/doi/10.1126/science.abq6100
奇妙な金属で音を撮影 Shot noise in a strange metal
Liyang Chen,Dale T. Lowder,Emine Bakali,Aaron Maxwell Andrews,Werner Schrenk,Monika Waas,Robert Svagera,Gaku Eguchi,Lukas Prochaska,Yiming Wang,Chandan Setty,Shouvik Sur,Qimiao Si,Silke Paschen,and Douglas Natelson
SCIENCE 23 Nov 2023 Vol 382, Issue 6673 pp. 907-911 DOI: 10.1126/science.abq6100
Editor’s summary
Charge current in solids is carried by discrete entities called quasiparticles that give rise to associated shot noise. For the peculiar phase called the strange metal, however, this quasiparticle scenario is expected to break down, leading to a reduction in shot noise. Chen et al. tested this prediction by measuring shot noise in nanowires made of the heavy fermion material YbRh2Si2 in the strange metal phase. In these samples, shot noise was indeed reduced compared with the values measured in a comparable gold nanowire and with the theoretical expectations for a system of quasiparticles. —Jelena Stajic
Abstract
Strange-metal behavior has been observed in materials ranging from high-temperature superconductors to heavy fermion metals. In conventional metals, current is carried by quasiparticles; although it has been suggested that quasiparticles are absent in strange metals, direct experimental evidence is lacking. We measured shot noise to probe the granularity of the current-carrying excitations in nanowires of the heavy fermion strange metal YbRh2Si2. When compared with conventional metals, shot noise in these nanowires is strongly suppressed. This suppression cannot be attributed to either electron-phonon or electron-electron interactions in a Fermi liquid, which suggests that the current is not carried by well-defined quasiparticles in the strange-metal regime that we probed. Our work sets the stage for similar studies of other strange metals.
