New at Campus Wannsee: CoreLab Quantum Materials
This optical zone melting furnace is producing large single crystals. © M. Setzpfandt/HZB
A Laue apparatus is used for precise alignment of the crystals. © M. Setzpfandt/HZB
Phase transitions can be detetcted by measuring transport properties of the sample. © M. Setzpfandt/HZB
Helmholtz-Zentrum Berlin has expanded its series of CoreLabs for energy materials research. In addition to the five established CoreLabs, it has now set up a CoreLab for Quantum Materials. A research team from the HZB Institute for Quantum Phenomena in New Materials is responsible for the CoreLab and its modern equipment. The CoreLab is also open to experimenters from other research institutes.
Quantum phenomena are typically easiest to observe within perfect single crystals at very low temperatures. A team led by Prof. Dr. Bella Lake and Dr. Konrad Siemensmeyer has set up a dedicated CoreLab for Quantum Materials for producing and experimenting with such single crystals in the laboratory, or for preparing them for measurements at the neutron source BER II or the synchrotron light source BESSY II. External researchers are also welcome to use this CoreLab and benefit from the expertise of the HZB team.
Growth and preparation of single crystals
In many cases, the materials of interest are initially produced as microcrystalline powders and not as single crystals. Even the process of synthesising these powders is often difficult. It is therefore a key topic at this HZB CoreLab. In a powerful optical zone melting furnace, powder samples can be regrown as larger single crystals, which yield far more meaningful experimental results. Growing single crystals from powder samples requires a great deal of experience, which HZB possesses. A Laue apparatus is used for precise alignment of the crystals. Next, the crystals are cut in orientation with a wire saw or their surfaces polished in preparation for further experiments. The methods are highly flexible and suitable for all possible experiments. Samples are easily prepared here for experiments at the neutron source, at BESSY II, or in the lab. Less experienced users are closely supervised to ensure the success of their experiments.
Transport properties and phase transitions
Another room provides high magnetic fields, low temperatures with two “Physical Property Measurement Systems” and a sensitive SQUID magnetometer. These allow the measurement of transport properties such as thermal conductivity, magnetisation and specific heats of materials. Measuring these properties renders so-called phase transitions visible. These phase transitions have a correlation with quantum physical laws and indicate the formation of new structures within the material.
CoreLabs for users in academia and industry
As an operator of large facilities, HZB has great experience in organising external user operation. HZB is now also introducing this experience into the operation of its CoreLabs, which are equipped with latest generation, and sometimes unique, instruments and equipment for analysing and synthesising energy materials. International experimental guests and partners from industry are equally welcome here.
- Alternating currents for alternative computing with magnetsA new study conducted at the University of Vienna, the Max Planck Institute for Intelligent Systems in Stuttgart, and the Helmholtz Centers in Berlin and Dresden takes an important step in the challenge to miniaturize computing devices and to make them more energy-efficient. The work published in the renowned scientific journal Science Advances opens up new possibilities for creating reprogrammable magnonic circuits by exciting spin waves by alternating currents and redirecting these waves on demand.
- BESSY II: Heterostructures for SpintronicsSpintronic devices work with spin textures caused by quantum-physical interactions. A Spanish-German collaboration has now studied graphene-cobalt-iridium heterostructures at BESSY II. The results show how two desired quantum-physical effects reinforce each other in these heterostructures. This could lead to new spintronic devices based on these materials.
- Green hydrogen: MXenes shows talent as catalyst for oxygen evolutionThe MXene class of materials has many talents. An international team led by HZB chemist Michelle Browne has now demonstrated that MXenes, properly functionalised, are excellent catalysts for the oxygen evolution reaction in electrolytic water splitting. They are more stable and efficient than the best metal oxide catalysts currently available. The team is now extensively characterising these MXene catalysts for water splitting at the Berlin X-ray source BESSY II and Soleil Synchrotron in France.