SQUID Magnetometer (7 Tesla)

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At the Centre for Electronic Correlations and Magnetism of the University of Augsburg, the chair of Experimental Physics V focuses on the study of strongly correlated magnetic materials with new functionalities. Materials of interest are e.g. skyrmion hosts, frustrated magnets, low-dimensional spin systems, magnetoelectric compounds, and unconventional superconductors. Most of these materials are grown and carefully characterized in the chair, before they are studied by advanced methods like dielectric and optical spectroscopy, and magnetic resonance techniques. Besides x-ray structural analysis, the magnetic characterization by SQUID measurements is an inevitable tool for a reliable fundamental investigation of each new magnetic material. In many cases the investigations of magnetization and magnetic susceptibility go far beyond standard characterization, e.g. for determination of critical exponents at magnetic phase transitions, critical fields in superconductors, as well as the detailed scan of phase transitions between different magnetic phases. This vast number of mandatory measurements for each magnetic sample urgently demands a new powerful SQUID magnetometer, as the existing more than 20 years old machine is heavily overloaded and recently requires frequent maintenance. We apply for a SQUID magnetometer for DC- and AC-magnetization measurements in magnetic fields up to 7 Tesla maximum and in a temperature range from 2 K up to 400 K (helium cryostat) and from 300 K up to 1000 K (oven). The following options should be included: precise field regulation even for small fields (<0,5 mT), high-pressure cell for hydrostatic pressure up to 13 kbar, cryostat insert for electrical measurements, rotator for angular dependent measurements. The proposed new SQUID magnetometer will allow to accelerate and intensify the current and planned activities in the analysis of new multifunctional materials. It provides economy of time (factor 5-10) and an extended parameter regime (magnetic field, temperature, pressure). This is essential for the successful continuation of our projects within the Transregio TRR 80 (“From Electronic Correlations to Functionality”) and the Priority Program SPP 2137 (“Skyrmionics”) and it is prerequisite for the realization of various planned projects, described in the proposal.