A topological superconductivity model system with skyrmionic magnons as the mediating agents

The properties of topological superconductors, also known as “in-gap Majorana states,” distinguish them from other types of superconductors. These bound states can act as qubits, making topological superconductors especially encouraging for the production of quantum-figuring innovations.

Quantum skyrmion crystals, which combine swirling configurations of atomic magnetic dipoles (spins) with superconductors, have recently been the subject of some research by physicists. The greater part of these endeavors proposed sandwiching quantum silver precious stones between superconductors to accomplish topological superconductivity.

An alternative model system of topological superconductivity, devoid of superconducting materials, was recently proposed by Kristian Mland and Asle Sudb, two researchers at the Norwegian University of Science and Technology. Instead, the sandwich structure of a heavy metal, a magnetic insulator, and a normal metal would be used in this theoretical model, which was first presented in Physical Review Letters. The heavy metal would cause the magnetic insulator to produce a quantum symphony crystal.

“While we have not personally created these systems for experimental purposes, we are suggesting materials that could be used to build such systems and investigate their characteristics,”

Asle Sudbø, researchers at the Norwegian University of Science and Technology,

According to Sudb, who spoke with, “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 symion crystals could affect normal metallic states and possibly lead to an unusual type of superconductivity.”

“The experimental work of Heinze et al. on realizations of quantum skyrmion crystals, as well as two of our own papers on quantum skyrmion crystals, are among the previous works that in particular have inspired us and that we have been building on.”

Skyrmion crystals can be created in actual physical systems, as demonstrated by Stefan Heinze of the University of Kiel and his colleagues at the University of Hamburg in a 2011 paper. Sudb and Mland’s newly proposed model system of topological superconductivity is based on a series of predictions that they made in response to the team’s previous work.

Depictions of the ground states of the skyrmion crystals in the magnetic monolayer. Color indicates the out-of-plane component, while arrows indicate the in-plane component. Credit: Kristian Mæland and Asle Sudbø.

“We most definitely have not made these frameworks tentatively; however, we are proposing materials that could be utilized to make such frameworks and studying their properties,” Sudb said. “By sandwiching a normal metal with a very specific spin system in which the spins form skyrmions in a repeated pattern, a skyrmion crystal, we specifically investigated a novel method for creating topological superconductivity. Past recommendations for topological superconductivity proposed sandwiching syrmion precious stones with superconductors. The sandwich does not require a superconductor because of our method.

Sudb and Mland attempted to determine the properties of their proposed model system through a series of calculations, despite the fact that they were unable to demonstrate it experimentally. They determined a non-trivial topology for a property of the system’s induced superconducting state, the so-called superconducting order parameter.

According to Sudb, “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.” “We were able to create a model system.” While previous proposals used a sandwich structure of magnetic insulators and other superconductors, our system consists of a normal metal and a magnetic insulator.”

In the not-too-distant future, new research may attempt to replicate the model system that these researchers have proposed in an experimental setting, examining its properties and potential applications in quantum computing. In the meantime, Sudb and Mland intend to theoretically investigate alternative approaches to unconventional superconductivity.

“Overall terms, we will seek unpredictable superconductivity and courses to topological superconductivity in heterostructures by including attractive encasings with uncommon and eccentric ground states as well as clever sorts of twist excitations out of the ground state,” Sudb said.

More information: Kristian Mæland et al, Topological Superconductivity Mediated by Skyrmionic Magnons, Physical Review Letters (2023). DOI: 10.1103/PhysRevLett.130.156002

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