Research on New Materials
Besides providing access for users to high magnetic fields, there exists as well a dedicated in-house research program at the HLD. In concert with several other research groups of the HZDR, the research program of the HLD is focused on investigations of novel strongly correlated electron systems, latest superconducting and magnetic materials, (magnetically) doped semiconductors, nanostructures, and, in particular, such materials which comprise several of these properties and gain much interest due to fundamental scientific and applied technological reasons. On the following research fields, recognized in-house research attracts international attention:
- reconnaissance of the electronic structure of novel materials, in particular based on the observation of magnetic quantum oscillations;
- investigations of the properties of magnetic and superconducting materials;
- studies of phase transitions in high magnetic fields and determination of field-induced phases;
- resonance experiments in energy scales not yet accessible, i.e., at very high magnetic fields and using high laser-light intensities making use of the infrared radiation produced in the free-electron lasers at ELBE;
- establishing the HLD to a world-leading user facility for experiments and applications in very high magnetic fields.
|Different critical temperatures for different materials|
|picture: Marc Uhlarz / HZDR|
A HLD research result made it around the world: Scientists from the HLD and the TU Dresden were able to verify with an intermetallic compound of bismuth and nickel that certain materials actually exhibit the two contrary properties of superconductivity and ferromagnetism at the same time. A phenomenon that had only been demonstrated around the globe on a small number of materials and which might provide highly interesting technological opportunities in future.
High-temperature superconductors, which are relevant even for applications, have been investigated now for more than two decades. Nevertheless, since recently there has been a clear deficit on the knowledge of the Fermi-surface topology and of the electronic band-structure parameters. Only the recent development of high-resolution measuring techniques in low-noise pulsed-field magnets made it possible within the last years to acquire excellent results in this field. Pioneering work has been performed at the pulsed-field lab in Toulouse. Also, the HLD has succeeded in cooperation with a research group from the Walther-Meissner Institute in Garching, Germany, to observe magnetic quantum oscillations in electrical-transport measurements of electron-doped high-temperature superconductors.
A prominent example for research on new superconductors is the recent discovery of the occurrence of high-temperature superconductivity in the iron-pnictide systems. Beside the knowledge of the electronic band structure making use of quantum-oscillation measurements, the exact determination of the superconducting phase boundary as function of the applied field is of particular interest. The critical magnetic field of these superconductors can often be determined at low temperatures only with the help of pulsed-magnetic-field experiments. Differently than in many cuprate-based high-temperature superconductors, the entire field-temperature phase diagram of the iron-pnictide systems may be accessible. Hence, investigations of these materials may contribute more efficiently to gain better insight into the nature of collective Cooper-pair condensation at high temperatures.