Low vibration and low temperature closed-cycle cryostat for oxide MBE and laser-ARPES

用于氧化物 MBE 和激光 ARPES 的低振动和低温闭环低温恒温器

• 批准号: RTI-2020-00634
• 负责人: Sawatzky, George
• 金额: $ 10.93万
• 依托单位: University of British Columbia
• 依托单位国家: 加拿大
• 项目类别: Research Tools and Instruments
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=693783
• 关键词: Low; vibration; low; temperature; closed

This proposal is for the purchase of a closed-cycle recirculating chiller to upgrade the low temperature cryostat of the Quantum Materials and Devices Foundry (QMDF) led by George Sawatzky at UBC. The goal of the facility is to study the properties of materials comprised of layers of different compounds known as heterostructures, and phenomena arising at the interfaces between these layers. In particular, QMDF aims at engineering transition-metal oxide and dichalcogenide heterostructures, growing them by molecular beam epitaxy (MBE), and to comprehensively characterizing them in situ as they are being fabricated layer-by-layer. While QMDF will be used to explore a large number of phenomena, the immediate goal is to study unconventional superconductivity in thin film iron pnictides and nickelates, as they might be the key materials to answer the most intriguing question in modern condensed matter: what is the nature of unconventional superconductivity and how to create a room temperature superconductor. *******The cryostat to be upgraded is used for mapping of electronic bands in heterostructures by means of angle resolved photoemission spectroscopy (ARPES), the main characterization method associated with the facility. Unlocking the mystery of high-temperature superconductivity might be hiding in subtle details of the electronic band structure, and it is imperative to gain information with high signal to noise ratio and high energy and momentum resolution. In turn, this requires the samples under investigation to be held at cryogenic temperatures for an extended time while under study. The challenge is to find a cost-effective method of keeping the sample stable to better than 0.1K at all cryogenic temperatures down to 3K.*******Low temperature experiments today can be undertaken using two methods: (1) the direct use of liquid helium (flow cryostat, currently used); or (2) the use of a closed cycle refrigeration system. While the latter allows us to reach lower temperatures using pumped helium, it cannot run constantly for more then a few days, is prone to sample temperature and position drift, and is exorbitantly expensive to run. On the one hand, a typical ARPES facility equipped with a flow cryostat costs about $100,000/year consuming one of the earth's most precious and non-renewable resources, releasing much of it back into the atmosphere. On the other hand, a typical closed cycle cryostat is not able to operate below about 10K. Our goal, is to combine the technological advances in cryogenic design that will allow UBC's flow cryostat to reach very low temperatures with a cryogen free refrigeration system produced by Janis Research Company.*******This upgrade will provide the Quantum Materials and Devices Foundry with dramatically increased experimental running times, which are essential for accurately measuring the electronic properties of some of the new exotic samples that are now being routinely grown at UBC.

该建议是为了购买闭合循环冷却器，以升级由UBC乔治·萨茨基（George Sawatzky）领导的量子材料和设备铸造厂（QMDF）的低温低温恒温器。该设施的目的是研究由称为异质结构的不同化合物层组成的材料的性质，以及在这些层之间的界面上产生的现象。尤其是QMDF旨在工程过渡金属氧化物和二甲藻元化的异质结构，通过分子束外延（MBE）生长它们，并在它们被逐层制造时全面表征它们。虽然QMDF将用于探索大量现象，但近期目标是研究薄膜铁皮细胞和镍盐中的非常规超导性，因为它们可能是回答现代凝结问题中最有趣的问题的关键材料：非常规超级强制性以及如何创建室温超级强制性的方式是什么。 *******通过角度分辨光发射光谱（ARPES），将要升级的低温恒温器用于绘制异质结构中的电子带，这是与设施相关的主要特征方法。解锁高温超导性的奥秘可能隐藏在电子带结构的细节中，并且必须获得具有高信号与噪声比，高能量和高能和动量分辨率的信息。反过来，这要求研究的样品在研究期间长时间在低温温度下进行。面临的挑战是找到一种具有成本效益的方法，即在所有低温温度下降至3K时，将样品稳定至0.1K。*******今天可以使用两种方法进行低温实验：（1）直接使用液氦（Flow Cryostat，目前使用）；或（2）使用封闭的周期制冷系统。尽管后者使我们能够使用泵送的氦气达到较低的温度，但它不能持续几天不断运行，容易容易样品温度和位置漂移，并且运行昂贵。一方面，配备流动式低温恒温器的典型ARPES设施每年的价格约​​为100,000美元，消耗了地球上最珍贵，最不可再生的资源之一，其中大部分释放回了大气中。另一方面，典型的封闭循环低温恒温器无法在大约10k以下操作。 Our goal, is to combine the technological advances in cryogenic design that will allow UBC's flow cryostat to reach very low temperatures with a cryogen free refrigeration system produced by Janis Research Company.*******This upgrade will provide the Quantum Materials and Devices Foundry with dramatically increased experimental running times, which are essential for accurately measuring the electronic properties of some of the new exotic samples that are now being routinely grown at UBC。