近日，德国马克斯普朗克固体化学物理研究所的Andrew P.Mackenzie及其研究小组取得一项新进展。经过不懈努力，他们对高导电性氧化物PdCrO₂中的普朗克行为进行了研究。相关研究成果已于2023年8月28日在国际知名学术期刊《美国科学院院刊》上发表。

该研究团队通过控制引入点无序，测量热导率和洛伦兹比，以及研究其高温熵的来源来研究“普朗克金属”物理学。T线性电阻率主要是由弹性散射引起的，是几种散射机制的总和。值得注意的是，这个和导致散射率在普朗克值k_BT/h的10%以内。

据悉，层状铜铁矿金属PdCrO₂是耦合到相邻的莫特绝缘CrO₂层中局域自旋的高导电性Pd层近藤的天然异质结构。在高温下，它具有T线性电阻率，这在同构但非磁性的PdCoO₂中没有看到。近藤耦合的强度是已知的，生长的晶体纯度极高，费米表面非常简单且实验上已知。因此，它是研究“普朗克金属”物理学的理想材料平台。

附：英文原文

Title: Investigation of Planckian behavior in a high-conductivity oxide: PdCrO₂

Author: Zhakina, Elina, Daou, Ramzy, Maignan, Antoine, McGuinness, Philippa H., Knig, Markus, Rosner, Helge, Kim, Seo-Jin, Khim, Seunghyun, Grasset, Romain, Konczykowski, Marcin, Tulipman, Evyatar, Mendez-Valderrama, Juan Felipe, Chowdhury, Debanjan, Berg, Erez, Mackenzie, Andrew P.

Issue&Volume: 2023-8-28

Abstract: The layered delafossite metal PdCrO₂ is a natural heterostructure of highly conductive Pd layers Kondo coupled to localized spins in the adjacent Mott insulating CrO₂ layers. At high temperatures, T, it has a T-linear resistivity which is not seen in the isostructural but nonmagnetic PdCoO₂. The strength of the Kondo coupling is known, as-grown crystals are extremely high purity and the Fermi surface is both very simple and experimentally known. It is therefore an ideal material platform in which to investigate “Planckian metal” physics. We do this by means of controlled introduction of point disorder, measurement of the thermal conductivity and Lorenz ratio, and studying the sources of its high-temperature entropy. The T-linear resistivity is seen to be due mainly to elastic scattering and to arise from a sum of several scattering mechanisms. Remarkably, this sum leads to a scattering rate within 10% of the Planckian value of k_BT/h.

DOI: 10.1073/pnas.2307334120

Source: https://www.pnas.org/doi/10.1073/pnas.2307334120