Cryogen-free dilution refrigerator with 3D vector magnet for transport studies of quantum materials

• Subject Area: Condensed Matter Physics
• Term: Funded in 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 526077868

We aim to develop the LMU‘s research endeavours on quantum materials by the acquisition of a dilution refrigerator equipped with a (9,1,1)T vector magnet. This complete apparatus will fill a critical void at the LMU where the absence of such a system hinders competitive research on quantum materials. Indeed, a dilution refrigerator permits to cool any material of interest down to 8mK with a stabiblity below 5mK. This temperature is low enough to suppress thermal fluctuations and thus to let quantum effects, stemming from electronic correlations, manifest themselves. Once in this strongly degenerate ground state, the three-dimensional vector magnet grants a complete control of the spin polarization. This allows to study in-depth a major conundrum of modern condensed matter physics: magnetic excitations and their interplay/competition with other quantum electronic phases such as superconductivity. We aim to probe these correlated phenomena by two complementary techniques, low-frequency (DC) and high-frequency (RF) electronic transport, thanks to an array of highly-filtered 48 DC and 8 RF transmission lines. High-quality filtering of the transmission lines is paramount to suppress electromagnetic heating of the electrons at low temperatures and preserve the quantum phenomenology. To complete our measurement setup, composed of pre-amplifiers and lock-in amplifiers, we wish to acquire acquire a high-definition oscilloscope and a network analyzer. Finally, we wish to buy a cryogen-free system for both simplicity of usage, as the equipement will be shared among the LMU, and long-term economy in light of the ever increasing price of liquid helium.

• DFG Programme: Major Research Instrumentation
• Major Instrumentation: Kryogenfreier Mischkryostat mit 3D-Vektormagnet für Transportstudien von Quantenmaterialien
• Instrumentation Group: 8550 Spezielle Kryostaten (für tiefste Temperaturen)
• Applicant Institution: Ludwig-Maximilians-Universität München
• Leader: Professor Dr. Dmitri K. Efetov