Cryogen-free 14 Tesla magnet system for microwave spectroscopy, magnetometry, and transport

• Subject Area: Condensed Matter Physics
• Term: Funded in 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 575701443

A cryogen-free multifunctional 14 Tesla magnet system for temperature- and field-dependent magnetic measurements is being requested. In order to cover the broad spectrum of different material classes (nanoparticles, 2D materials, epitaxial films, and bulk samples) that are being investigated in various collaborative projects and individual research grants, broadband microwave spectroscopy, magnetometry, and magneto-transport options are required for the fundamental analysis of magnetic properties. In particular, the system will be used as a magneto-cryogenic platform for performing broadband microwave spectroscopy. This method uses special inserts and sample holders with suitable coaxial cables. These highly specific measurements are based on proprietary hardware and software that is connected to the commercial system. Broadband microwave spectroscopy up to 60 gigahertz and its analysis with a vector network analyzer will allow temperature-, frequency-, field-, and angle-dependent ferromagnetic resonance to be performed on highly anisotropic materials. From this, the magnetic anisotropy, the gyromagnetic ratio, and the damping and inertia of the magnetization can be determined. The extension to high frequencies and high fields will also allow antiferromagnetic resonance to be measured, e.g., on hematite nanostructures, which is the subject of current research in magnonics. Magnetometry provides fundamental magnetic parameters. Permanent magnets exhibit high anisotropy fields, so that the 14 Tesla magnet system makes it possible to drive the samples to saturation while simultaneously varying the temperature over a wide range (2-1000 Kelvin). Magnetocaloric materials such as antiperovskites often exhibit a phase transition shift as function of field and thermal hysteresis, which must be characterized up to high fields. Current projects are investigating high-entropy alloys, transition metal carbides and borides, and mixed systems of ferromagnetic and antiferromagnetic materials. These also exhibit very high saturation fields. Measurements of the (magneto)transport properties make it possible to correlate the electronic properties with the magnetism of the sample systems. In particular, in epitaxial films with low magnetization on insulating substrates, the magnetic properties and the Hall effect can be determined by field- and temperature-dependent resistance measurements. Phase transitions can thus be identified and the change in resistance exploited for sensor functions. The University of Duisburg-Essen does not have a comparable multifunctional magneto-cryogenic platform for measuring magnetic properties up to 14 Tesla.

• DFG Programme: Major Research Instrumentation
• Major Instrumentation: Kryogenfreies 14 Tesla Magnetsystem für Mikrowellenspektroskopie, Magnetometrie und Transport
• Instrumentation Group: 0150 Geräte zur Messung der magnetischen Materialeigenschaften
• Applicant Institution: Universität Duisburg-Essen
• Leader: Professor Dr. Ulf Wiedwald