3-He cooler for SQUID magnetometer

磁化强度和磁化率是表征固体和分子的基本性质。我们的团队专注于具有强电子相关性的新材料，这些材料来自部分占据的d-或f-壳层。我们感兴趣的是物质的新量子态及其低能激发，例如重费米子系统中量子临界引起的非费米液体行为，非常规超导性，磁挫折和自旋液体行为。为此，我们利用各种技术合成单晶和多晶，薄膜和异质结构。为了表征和详细研究温度低于1 K的磁性和热力学性质，需要高分辨率的SQUID磁强计。我们申请为现有的现代SQUID磁强计提供3-He冷却选项，其允许在DC中以高达5 x 10-8 emu的分辨率检测磁矩，在0.46 ~ 1.8K的温度范围内测量了磁化强度和交流磁化率。这将显著地将现有的温度范围从1.8 K向下端扩大到400 K，这对于检测上述材料的磁性是必不可少的，因为测量低至1.8 K是不够的。所要求的主要研究仪器将允许在我们现有的SQUID磁强计快速例行自动直流和交流测量。利用所要求的3-He冷却器的计划研究项目的目标是：· 几何阻挫近藤晶格中金属自旋液体行为的证明· 新型层状重费米子金属的设计与磁性表征 几何阻挫稀土磁体中量子自旋液体行为和场诱导相的研究 绝热退磁冷却到毫开尔文温度的新材料的磁性表征

Magnetization and susceptibility are essential properties for the characterization of solids and molecules. Our group focusses on new materials with strong electronic correlations, arising from partially occupied d- or f-shells. We are interested in novel quantum states of matter and their low-energy excitations, such as non-Fermi liquid behavior arising from quantum criticality in heavy-fermion systems, unconventional superconductivity, magnetic frustration and spin liquid behavior. To this end, we synthesize single and polycrystals, thin films and heterostructures utilizing various techniques. For the characterization and detailed investigation of the magnetic and thermodynamic properties down to temperatures below 1 K, high-resolution SQUID magnetometry is required.We apply for a 3-He cooling option for an existing modern SQUID Magnetometer at our chair, which allows the detection of magnetic moments with resolution up to 5 x 10-8 emu in DC-magnetization and AC susceptibility measurements in the temperature range between 0.46 and 1.8 K. This would significantly enlarge the existing temperature range from 1.8 to 400 K towards the lower end, which is essential for the detection of magnetic properties of the above materials, since measurements down to 1.8 are insufficient. The requested Major Research Instrumentation will allow in our existing SQUID magnetometer quick routine automatic DC and AC measurements. Goals of the planned research projects utilizing the requested 3-He cooler are:• Proof of metallic spin liquid behavior in geometrically frustrated Kondo lattices• Design and magnetic characterization of novel layered heavy-fermion metals• Investigation of quantum spin liquid behavior and field-induced phases in geometrically frustrated rare-earth magnets• Magnetic Characterization of new materials for adiabatic demagnetization cooling to Millikelvin temperatures