Cryogen-free dilution refrigerator system with selected options

具有选定选项的无制冷剂稀释制冷系统

• 批准号: 448942660
• 金额: --
• 依托单位: Julius-Maximilians-Universität Würzburg
• 依托单位国家: 德国
• 项目类别: Major Research Instrumentation
• 财政年份: 2020
• 资助国家: 德国
• 起止时间: 2019-12-31 至 无数据
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/448942660?language=en
• 关键词: Cryogen; free; dilution; refrigerator; system

We propose to purchase a cryogen-free dilution refrigerator appropriate for the incorporation of a SQUID magnetometer, for the purpose of studying magnetization properties at millikelvin temperatures. While Squid operating down to about 1.5K are omnipresent, systems working at lower temperatures are absent in the field. There are however significant questions, with regards to magnetic and superconducting properties of Topological insulators which require precisely such an instrument to address. For example, consider the electrical quantum effects that form the basis of the new SI unit system. A promising new material class for applications in this field are the magnetic topological insulators, which allows the quantum Hall resistors to be realized without a magnetic field, in the form of the quantum anomalous Hall effect (QAHE). However, the nature of the ferromagnetic state in these topological insulators is still unclear. To understand this state, it must be measured under the same conditions where the samples exhibit the QAHE, which at present is well below 1K. A major objective is thus to develop techniques to accurately characterize the magnetic and structural properties of the QAHE devices, especially V-doped (Bi,Sb)Te system with high resolution using the SQUID sensor that can work in variable temperatures from 30K down to 10mK, which will allow us to answer some fundamental physics questions on the nature of the ferromagnetic state in this material. In addition to this primary aim, the availability of mK-SQUID will be beneficial to projects on topological superconductivity and to our other investigation on magnetic TIs in general. This instrument will provide a unique functionality in this field, and will allow us to significantly move forward the understanding of these important novel materials.

我们建议购买一个无冷冻剂的稀释冰箱适合纳入一个SQUID磁强计，研究在毫开尔文温度下的磁化特性的目的。虽然Squid工作温度低至约1.5K是无处不在的，但在较低温度下工作的系统在该领域是不存在的。然而，关于拓扑绝缘体的磁性和超导性质，存在一些重要的问题，这些问题需要精确地使用这样的仪器来解决。例如，考虑形成新SI单位制基础的电量子效应。在这一领域应用的一个有前途的新材料类别是磁性拓扑绝缘体，它允许量子霍尔电阻器在没有磁场的情况下以量子反常霍尔效应（QAHE）的形式实现。然而，这些拓扑绝缘体中的铁磁状态的性质仍然不清楚。为了理解这种状态，必须在样品表现出QAHE的相同条件下进行测量，目前QAHE远低于1 K。因此，一个主要目标是开发技术，以准确地表征QAHE设备的磁和结构特性，特别是V掺杂的（Bi，Sb）Te系统，使用SQUID传感器，可以在30 K到10 mK的可变温度下工作，这将使我们能够回答一些基本的物理问题，在这种材料中的铁磁状态的性质。除了这个主要目标，mK-SQUID的可用性将有利于拓扑超导性的项目和我们的其他研究磁性TI一般。该仪器将在这一领域提供独特的功能，并将使我们能够大大推进对这些重要新材料的理解。