Theme and goal
The electronic band structure of a material contains information about all of the electrons in which are relevant for bonding and electronic properties in a solid. It also contains information on the electron spin, and the electrons interactions with each other impurities, vibrations, spin waves, and more. It is of great interest to try to directly measure the electronic band structure, and hence to gain access to this information. Over the last decade, the instrumentation available has improved dramatically, thus it now possible to measure the electronic band structure with exceptional energy, momentum, and spatial resolutions.
The primary goals are to provide experimental competence to support the theoretical activities within QuSpin, to produce research contributions in important and topical fields, and at an internationally respected level. We also strive to bring interesting and up-to-date research work into the undergraduate classroom, to educate Master students, to contribute to the career development of young scientists and to enable high-quality Ph.D. theses to be produced.
Our research predominantly focuses on the interaction of electrons (especially their spin) within a solid. For example, the coupling of electrons with each other (mediated by vibrational waves or spin waves) can give rise to superconductivity, which allows an electrical charge to move without any losses. Unusual forms of coupling between spin and charge allow the efficient conversion of electrical signals into low loss spin signals - and this can also open new avenues for low loss (or lossless) signal transmission, storage, and manipulation. Finally, quantum confinement of charge and spin lies at the heart of the fas developing field of quantum computing.
Most of the methods we use come under the category of “photoelectron spectroscopy” and are based in Einstein’s photoelectric effect, for which he received the Nobel Prize in 1921. Using a refinement of this effect, it is possible to understand chemical bonding within a solid (a discovery which earned Kai Seigbahn the Nobel Prize in 1981), and more recently,it has also been shown that the same method can reveal the spectral function (closely related to the electronic band structure). Furthermore, this information can be resolved by energy,momentum, and spin and the newest instruments also facilitate good spatial resolution. We operate two instruments at NTNU which are based on various refinements of this method. We also make significant use of similar instruments at international synchrotron radiation facilities. In 2019 we will purchase and install a state-of-the-art spin-resolved photoelectron microscope to extend the range of possible measurements at NTNU.
For current activities, see QuSpin Annual Report 2021.