Electron spin resonance spectrometer

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At the Center for Electronic Correlations and Magnetism (ECM) at 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. frustrated magnets, low-dimensional spin systems, magnetoelectric compounds, skyrmion hosts, magnetic Weyl semimetals and unconventional superconductors. Most of these materials are grown and carefully structurally and magnetically characterized in the chair, before they are studied by advanced methods like dielectric and optical spectroscopy, atomic force microscopy, as well as electron and nuclear magnetic resonance techniques.Regarding magnetic resonance, electron spin resonance (ESR) plays a central role, both for the general characterization of new magnetic materials as a check of sample purity and for the deeper study of local electronic and magnetic properties to identify microscopic interactions. Often ESR directly probes the spin system of interest, which determines the physics of the material under investigation. Therefore, in many cases the experimental effort goes far beyond standard characterization, e.g. for determination of critical exponents at magnetic phase transitions or for investigation of magnetic anisotropy, whereby detailed measurement protocols have to be followed dependent on sample temperature and orientation of the sample in the magnetic field. This vast number of mandatory measurements for each magnetic sample urgently demands a new powerful ESR spectrometer, as the existing more than 20 years old machine is heavily overloaded and recently requires frequent maintenance.We apply for an ESR spectrometer for continuous-wave operation at X-band (9.4 GHz) and Q-band (34 GHz) frequencies. The modern technology of the microwave bridge and the signal processing unit allows an improved resolution and higher velocity in data recording as compared to the existing device. An electromagnet for magnetic fields up to 1.8 Tesla and several cryostats for helium- and nitrogen temperature control are already available in the laboratory. In addition, the present spectrometer will continue to be used to allow for enough operation time for the up to eight users.The proposed new ESR spectrometer will allow to accelerate and intensify the current and planned activities in the analysis of new multifunctional materials. 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.