Quantum transport of spin and charge
Recent years have seen the emergence of a plethora of novel ideas for intelligent designs of devices exploiting physical effects originating with quantum transport of spin and charge across junctions in various hybrid structures. These hybrid structures are based on a combination of different types of materials with functional properties such as superconductors, magnets, paramagnetic metals, semiconductors, and insulators.
The interplay between different types of order stemming from spontaneously broken symmetry or from a topological origin give rise to new physics that is of interest both from a fundamental viewpoint as well as in terms of possible applications.
The utilization of electricity and magnetism lies at the very heart of most major technological developments over the last centuries. Whereas electricity pertains to the motion of charged particles, magnetism can also be induced by an intrinsic property of electrons known as spin. The study of electronics and its implications has a long history, but in recent years spintronics has grown enormously as a research field, based on the idea that the electron spin may form centrepiece in future technological applications. In the search for functionalities utilizing ideas involving the spin of electrons, a subfield known as superspintronics has emerged from its predecessor. The idea is to combine the useful properties of superconductors with spin generation and manipulation. An intrinsic property of superconductors is that they offer a dissipationless flow of electric currents. The synthesis of this property and the spinpolarization of currents offered by ferromagnets adds up to the possibility of frictionless spincurrents.
Existing applications that are based on the interplay between superconductivity and magnetism include the superconducting quantum interference device (SQUID) and modern magnetic resonance imaging (MRI) technology, which both are vital in biomagnetism technology.
Whereas the study of quantum transport of charge and spin certainly offers new progress in terms of technological applications, it should be emphasized that this field of research is central in understanding issues related to fundamental physics. In particular, the wavelike nature of particles becomes crucial in mesoscopic and nanometer scale devices and strongly influences the resulting transport characteristics. The study of charge- and spin-transport therefore serves not only the purpose of exploring novel functionalities, but is also vital in terms of gaining a more thorough understanding of the manifestation of quantum mechanical effects in nanometer scale systems.
Our research includes the study of spin- and charge-currents in superconductors, ferromagnets, antiferromagnets, topological insulators, graphene, and in materials with strong spin-orbit coupling.