Spin dynamics in Kondo lattices at low temperatures and frequencies

低温和频率下近藤晶格中的自旋动力学

• 批准号: 225713324
• 负责人: Dr. Marc Scheffler
• 金额: --
• 依托单位: Max-Planck-Institut für Chemische Physik fester Stoffe (MPI CPfS)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2013
• 资助国家: 德国
• 起止时间: 2012-12-31 至 2018-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/225713324?language=en
• 关键词: Spin; dynamics; Kondo; lattices; low

Kondo lattices (lattices of local magnetic moments that interact with conduction electrons) are model systems for strong electronic correlations in solids. In principle, the dynamics of local spins can be studied with electron spin resonance (ESR). But for the case of Kondo lattices at low temperatures, one expects that the local moments are shielded by conduction electrons, thus preventing ESR. Surprisingly, the heavy-fermion material YbRh2Si2 exhibits pronounced ESR at low temperatures. This ESR is interpreted as a resonance of the metallic heavy fermions, but it is clearly impacted by the local moments of the underlying Kondo lattice. A deeper understanding of this ESR, taking into account the quantum-critical nature of YbRh2Si2, will enhance our general knowledge concerning the spin dynamics of Kondo lattices.We want to perform low-temperature ESR measurements to study the quantum-critical spin dynamics of YbRh2Si2. This is the first ever direct experimental access to the spin dynamics of a Kondo lattice close to a quantum-critical point. YbRh2Si2 is an established model material of quantum criticality, and here the relevant regime for our experiments is temperatures below 100 mK and magnetic fields smaller than the quantum-critical field of 70 mT. We employ superconducting planar resonators at frequencies between 1 GHz and 15 GHz, implemented in a dilution refrigerator (for temperatures down to approx. 30 mK). Our novel experimental techniques open up a previously unaccessible parameter regime for ESR and they are of interest for low-energy studies of spin dynamics that go far beyond our sample material YbRh2Si2.Understanding ESR at very low temperatures in general requires new theoretical approaches, as does our particular case of YbRh2Si2 close to a quantum critical point. Here, we will address the existing models for ESR in Kondo lattices, but we will also study the relation between the relevant energy scales of ESR (line width) and other experiments (e.g. specific heat). Combining new experimental ESR regimes and theoretical approaches will lead us to a deeper insight of quantum criticality of heavy-fermion systems.

Kondo Lattices（与传导电子相互作用的局部磁矩的晶格）是固体中强电子相关性的模型系统。原则上，可以使用电子自旋共振（ESR）研究局部旋转的动力学。但是，对于低温下的北多晶格的情况，人们期望局部矩被传导电子屏蔽，从而防止ESR。出人意料的是，重屈光度YBRH2SI2在低温下表现出明显的ESR。该ESR被解释为金属重量的共鸣，但显然受到底层北极晶格的当地时刻的影响。考虑到YBRH2SI2的量子性质的量子性质，对这种ESR有了更深入的了解，将增强我们关于近托晶格的自旋动力学的一般知识。我们希望执行低温ESR测量值，以研究YBRH2SI2的量子临界旋转动力学。这是有史以来第一次直接对接近量子关键点的围绕晶格的自旋动力学的实验访问。 YBRH2SI2是量子关键的既定模型材料，在这里，我们实验的相关状态是低于100 mk的温度，而磁场小于量子临界场的温度小于70吨的量子。我们以1 GHz至15 GHz之间的频率采用超导平面谐振器，该频率在稀释冰箱中实施（温度低至30 mk）。我们的新型实验技术为ESR开辟了一个以前难以接近的参数，它们对对旋转动力学的低能研究非常感兴趣，这些研究远远超出了我们的样本材料材料YBRH2SI2。在一般温度下以非常低的温度中理解ESR，需要新的理论方法，我们的特殊情况是YBRH2SI2的特殊情况。在这里，我们将解决近代晶格中ESR的现有模型，但是我们还将研究ESR（线宽度）的相关能量尺度与其他实验（例如特定热量）之间的关系。结合新的实验性ESR制度和理论方法将使我们对重力剂量系统的量子关键性有更深入的了解。

项目成果

On-Chip ESR Measurements of DPPH at mK Temperatures

mK 温度下 DPPH 的片上 ESR 测量

• DOI: 10.1016/j.phpro.2015.12.063
• 发表时间: 2015
• 期刊: Physics Procedia
• 作者: Wolfgang Voesch;Markus Thiemann;Daniel Bothner;Martin Dressel;Marc Scheffler
• 通讯作者: Marc Scheffler

Observing electron spin resonance between 0.1 and 67 GHz at temperatures between 50 mK and 300 K using broadband metallic coplanar waveguides

使用宽带金属共面波导在 50 mK 至 300 K 温度下观察 0 1 至 67 GHz 之间的电子自旋共振

• DOI: 10.1063/1.4921231
• 发表时间: 2015
• 期刊: Applied Physics Letters
• 影响因子: 4
• 作者: Yvonne Wiemann;Julian Simmendinger;Conrad Clauss;Lapo Bogani;Daniel Bothner;Dieter Koelle;Reinhold Kleiner;Martin Dressel;Marc Scheffler
• 通讯作者: Marc Scheffler

Superconducting coplanar microwave resonators with operating frequencies up to 50 GHz

工作频率高达 50 GHz 的超导共面微波谐振器

• DOI: 10.1088/1361-6463/aae2fa
• 发表时间: 2018
• 期刊: Journal of Physics D: Applied Physics
• 作者: Desirée S. Rausch;Markus Thiemann;Martin Dressel;Daniel Bothner;Dieter Koelle;Reinhold Kleiner;Marc Scheffler
• 通讯作者: Marc Scheffler

Angle-dependent electron spin resonance of YbRh2Si2 measured with planar microwave resonators and in-situ rotation

使用平面微波谐振器和原位旋转测量 YbRh2Si2 的角度相关电子自旋共振

• DOI: 10.1016/j.physb.2017.10.046
• 发表时间: 2018
• 期刊: Physica B-condensed Matter
• 影响因子: 2.8
• 作者: Linda Bondorf;Manfred Beutel;Markus Thiemann;Martin Dressel;Daniel Bothner;Jörg Sichelschmidt;Kristin Kliemt;Cornelius Krellner;Marc Scheffler
• 通讯作者: Marc Scheffler

Optimization of Coplanar Waveguide Resonators for ESR Studies on Metals

• DOI: 10.1088/1742-6596/592/1/012146
• 发表时间: 2015-01-01
• 期刊: INTERNATIONAL CONFERENCE ON STRONGLY CORRELATED ELECTRON SYSTEMS 2014 (SCES2014)
• 作者: Clauss, Conrad;Dressel, Martin;Scheffler, Marc
• 通讯作者: Scheffler, Marc