3-He cooler for SQUID magnetometer

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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