Topological superconductors are special kind of superconductors that exhibit in-gap Majorana states, among other unusual properties. Topological superconductors are particularly interesting for the development of quantum computing technologies since these confined states can function as qubits.
Recently, some physicists have started investigating the possibility of building quantum skyrmion crystals, which combine superconductors with swirling arrangements of atomic magnetic dipoles (spins). To create topological superconductivity, the majority of these initiatives proposed sandwiching quantum skyrmion crystals between superconductors.
Two researchers from the Norwegian University of Science and Technology, Kristian Maeland and Asle Sudb, have recently suggested a topological superconductivity alternative model system that does not use superconducting components. The heavy metal in this theoretical model, published in Physical Review Letters, produces a quantum skyrmion crystal in the magnetic insulator, which is then sandwiched between a normal metal and a magnetic insulator.
“We have been interested in low-dimensional novel types of quantum spin systems for a long time and were looking into the question of how quantum spin-fluctuations in quantum skyrmion crystals could affect normal metallic states and possibly lead to superconductivity of an unusual type,” Sudbø told Phys.org.
“Previous work that in particular have inspired us and that we have been building on, is the experimental work of Heinze et al on realizations of quantum skyrmion crystals, and two of our own papers on quantum skyrmion crystals.”
Stefan Heinze from the University of Kiel and his associates from the University of Hamburg demonstrated how skyrmion crystals may be realised in genuine physical systems in a paper that was published in 2011. These researchers’ earlier work served as a source of inspiration for Sudb and Maeland, who made a number of predictions that form the cornerstone of their topological superconductivity model system.
“We were able to create a model system where we can produce topological superconductivity in a heterostructure without having a superconductor a priori in the sandwich,” Sudbø said. “Our system is sandwich structure of a normal metal and a magnetic insulator, while previous proposals have involved a sandwich structure of magnetic insulators and other
superconductors.”
Future study may attempt to implement the model system suggested by these scientists in an experimental context in order to better understand its characteristics and possible uses in quantum computing. While this is going on, Sudb and Maeland intend to theoretically investigate alternative strategies for achieving unconventional superconductivity.
“In general terms, we will pursue unconventional superconductivity and routes to topological superconductivity in heterostructures of involving magnetic insulators with unusual and unconventional ground states as well as novel types of spin-excitations out of the ground state,” Sudbø said.
