under construction

The MaXRay research group at the University of Augsburg is developing a state-of-the-art laboratory instrument for spatially and temporally resolved magneto-optical measurements.
At its core is a High-Harmonic Generation (HHG) source that produces ultrafast, coherent extreme ultraviolet (XUV) radiation, enabling magnetic imaging with a spatial resolution down to 16 nm and a temporal resolution of 35 femtoseconds. This technology allows real-time observation of dynamic magnetic structures such as skyrmions and domain walls—previously only possible at large-scale facilities like synchrotrons or free-electron lasers.
The instrument combines two measurement branches: one for coherent X-ray holography and another for time-resolved magneto-optical Kerr effect (TR-MOKE) measurements in the visible range.
The group uses this setup to investigate fundamental principles of magnetic dynamics, develop novel imaging techniques, and explore topological magnetism. The instrument is central to multiple DFG- and EU-funded research projects and serves as a key component of next-generation magnetic imaging, operated in a modern laboratory at the University of Augsburg.

under construction

under construction

The Electron Spin Resonance (ESR) Laboratory provides three operating spectrometers: Two of them, the Bruker ELEXSYS E500 spectrometer and the advanced version E500A, are serving for standard measurements at X- (9.4 GHz) and Q-band (34 GHz) frequencies in magnetic fields up to 1.8 T. Both spectrometers are equipped with helium gas flow (Oxford Instruments) and N₂ gas flow (Bruker) cryostats working in the temperature range 4.2 - 300 K and 77 - 570 K, respectively. The third spectrometer is home-built from Bruker components with a large-gap electromagnet allowing for versatile experimental setups, as there are a ⁴He bath cryostat (1.6 - 4.2 K), a ³He cryostat (down to 0.7 K), and a special high-temperature oven (Bruker, 400 - 1000 K) as well as a home-built high-pressure cell (p < 30 kbar).

ESR measures the power absorbed from the transverse magnetic microwave field due to magnetic dipolar transitions between the Zeeman levels of paramagnetic atoms or ions split by the external static magnetic field. 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. The intensity of the signal is proportional to the pure spin susceptibility, the resonance field yields the g value, which bears information on spin-orbit coupling, crystal field, and corresponding local symmetries, and the line width is determined by the transverse spin-relaxation rate due to e.g. anisotropic exchange and dipolar fields.

Important milestones of our ESR investigations are the characterization of orbital order and orbital melting in LaMnO₃, the detection of a Griffiths phase in La_1-xSr_xMnO₃, the discovery of a universal relaxation behaviour in quasi one-dimensional spin-1/2 chain compounds, the evidence of Berezinskii-Kosterlitz-Thouless (BKT) type scenarios in quasi two-dimensional triangular-lattice Heisenberg antiferromagnets and on the three dimensional pyrochlore lattice of antiferromagnetic chromium oxide spinels. Recent highlights concern the skyrmion dynamics in lacunar spinels and the anisotropy of intermetallic skyrmion hosts.

 

© Universität Augsburg

Principle of magnetic resonance: microwave cavity between the pole caps of the electromagnet: The static field (0-1.8 T) is applied horizontally. The microwave (X-band: wavelength 3 cm) is fed by waveguides into the cavity. The magnetic microwave field oscillates vertically in the center of the cavity.  

 

 

© Universität Augsburg

ESR spectrometer: setup with helium bath cryostat in the electromagnet.

Crystal Growth and Characterization

The Chair of Experimental Physics V is equipped with comprehensive state-of-the-art facilities for crystal growth, sample preparation, and physical property characterization, enabling the synthesis and investigation of a broad range of quantum and functional materials.

Crystal Growth and Sample Preparation: Sample preparation is supported by a dedicated in-house glass-processing facility based on a hydrogen–oxygen flame system, which allows the fabrication, shaping, and sealing of quartz ampoules. Prior to sealing, the ampoules are evacuated using a turbomolecular pumping system, reaching vacuum levels down to 10^-6 mbar, thereby ensuring high-purity synthesis conditions. To accommodate various crystal-growth and synthesis techniques and post growth heat treatment, the laboratory operates several types of high-temperature furnaces optimized for specific thermodynamic conditions. For conventional solid-state reactions and molten-flux crystal growth, a set of programmable box (muffle) furnaces is available. These furnaces can operate continuously at temperatures up to 1300 °C and provide precise temperature control for long-duration synthesis experiments. Single crystals grown by the chemical vapor transport (CVT) method are synthesized in dedicated two-zone horizontal furnaces. These systems enable the creation of well-defined temperature gradients along the ampoule, which are essential for controlled transport and crystal growth. The furnaces operate at temperatures up to 1200 °C and allow independent regulation of the source and growth zones. For directional solidification and growth of large single crystals, the laboratory is equipped with vertical two-zone Bridgman furnaces. These systems are coupled to motorized translation and rotation stages, enabling precise control of pulling rates and crystal rotation during growth. The furnaces operate at temperatures up to 1200 °C and provide stable thermal gradients required for high-quality single-crystal growth. In addition, the laboratory is well-equipped with cutting and polishing facility.

Material Characterization: Phase identification, phase-purity analysis, and crystallographic characterization are routinely performed using a STOE Stadi P powder X-ray diffractometer equipped with Cu K_α radiation (λ ≈ 1.5406 Å). The instrument enables high-resolution room-temperature diffraction measurements and quantitative structural analysis of polycrystalline and powdered samples. Magnetic properties are investigated using a Quantum Design Magnetic Property Measurement System (MPMS). The system provides measurements over a broad temperature range from 1.8 K to 1000 K in magnetic fields up to 7 T. In addition to conventional DC magnetometry, the instrument supports AC susceptibility measurements and angular-dependent studies using a sample rotation option, allowing detailed investigations of dynamic magnetic phenomena and magnetic anisotropy. Electrical transport and thermodynamic properties are measured using a Quantum Design Physical Property Measurement System (PPMS). The system enables temperature-dependent and field-dependent magnetotransport measurements in the temperature range from 2 K to 300 K and magnetic fields up to 7 T. Furthermore, the PPMS is equipped for heat-capacity measurements, providing access to temperature- and field-dependent thermodynamic properties essential for identifying phase transitions and studying correlated-electron phenomena.

 

© Universität Augsburg

Transmission electron microscopy (TEM) is a high-resolution imaging technique in which an electron-transparent sample is probed with a beam of electrons.
Because of the short electron wavelength, TEM achieves very high spatial resolution, with our JEOL NEOARM instrument resolving individual atoms with a spatial resolution of approximately 60 pm. It also allows us to investigate the chemical composition of samples using energy-dispersive X-ray spectroscopy (EDS) and electron energy-loss spectroscopy (EELS).
Within the group, TEM is primarily employed for magnetic imaging using the Fresnel mode of Lorentz-TEM as well as differential phase contrast (DPC). These techniques visualize magnetic domain-wall structures in real space and reveal the type and chirality of domain walls while also detecting the topology of emergent spin textures. Combined with in-situ capabilities such as applied magnetic fields and controlled sample temperatures, this allows magnetization processes and spin textures in magnetic thin films and single-crystal lamellae to be studied directly at the nanoscale.
TEM thereby complements the group's X-ray-based imaging techniques and magnetic force microscopy (MFM), providing access to magnetic contrast at the highest spatial resolution.

 

Focused Ion Beam (FIB) patterning is a key nanofabrication technique used within the MaXRay research group to create and modify structures with nanometer precision.
By selectively milling or depositing material, FIB enables the fabrication of custom test samples, magnetic nanostructures, and high-precision apertures required for advanced X-ray and extreme ultraviolet (XUV) imaging experiments. In particular, FIB-fabricated masks and holographic reference structures are essential components for coherent X-ray holography using the group’s High-Harmonic Generation (HHG) source and large-scale synchrotron facilities.
The technique also supports the development of novel imaging concepts and sample environments tailored to studies of ultrafast magnetic phenomena. By providing direct access to nanoscale patterning, FIB bridges sample preparation and imaging, helping to advance next-generation magnetic microscopy and nanoscience research.