Theme and goal 

An electron has a spin in addition to its charge. The mobile charge carriers are the basis of conventional electronics and spintronics. In metals and semiconductors, electric fields induce currents. In magnets, a spin current occurs as well. In superconductors in contact with magnetic materials, charge and spin can flow without dissipation. In insulators, there are no moving charges. Spin information can, nevertheless, propagate. While electrons are immobile in insulators, another entity conveys information. At equilibrium, the electron spins become ordered. In response to external forces, the ordered pattern of the spins can be disturbed. The disturbance can take forms like spin waves or other dynamical spin textures.

We aim to determine how spins in magnetic materials connect to mobile electrons in adjacent semiconductors, metals, or superconductors. One aspect is to replace moving charges with magnetic insulators´ dissipation coherent and incoherent spin excitations. Another is to utilize superconductors in contact with magnetic materials to enable new ways of dissipationless flow of spin and charge. Additionally, coupling THz spin dynamics in antiferromagnets with conductors can facilitate new ways of creating THz electronics. In these systems, we can also enable unprecedented control of electron-electron, electron-magnon, and magnon-magnon interactions. These features can open doors toward creating new paths for magnon and exciton condensation, superfluidity, and superconductivity. Furthermore, since spin signals in these systems have extremely low power dissipation, overcoming the limitations can enable low-power technologies such as oscillators, logic devices, non-volatile random access memories, interconnects, and even quantum information processing.

Key questions

We focus on the fundamental challenges facing quantum spintronics. Key questions are how spin can transfer from magnetic materials to conductors and superconductors, how far and how spin propagates in insulators, conductors, and superconductors, how we can control electron and magnon correlations that cause new states of matter, and how to detect these phenomena.

For current activities, see QuSpin Annual Report 2025.

Theme and goal 

In classical physics, matter exists in one of four different states: gas, liquid, solid, or plasma. However, this classification is too crude to capture the wealth of fascinating physics that emerges within each of these states. For instance, not all solid states behave in the same way.

According to the quantum mechanical description of physics, various solid materials will behave in very different ways. Some materials are magnetic, some do not conduct currents of electric charge, while others can carry currents of not only charge but also a quantum property known as spin. This property is closely related to magnetism and is a fundamental trait of most elementary particles.

It turns out that some materials can conduct electric currents without any energy loss: so-called superconductors.The origin of superconductivity is quantum mechanical, but that does not mean superconductivity only occurs at microscopic length scales invisible to the naked eye. Large chunks of materials can be superconducting, making this phenomenon a macroscopic manifestation of quantum physics. Magnetism is another example of a phenomenon which originates from quantumphysics. When materials such as superconductors and magnets, having very different properties, are combined, things get interesting. This is one of the core motivations behind the field of superconducting spintronics where one studies precisely what happens when magnets are placed in close proximity to superconductors.

We have two main goals guide our research: Firstly, the most important goal is to discover new quantum mechanical phenomena that emerge when combining superconductors with other materials that have fundamentally different properties. A particular emphasis is on spin-dependent quantum effects that arise when magnetic materials are placed in contact with superconductors. Secondly, we focus on discovering specific phenomena that may be relevant to the development of memory technology and information transfer based on superconductors. This is closely related to how transport of charge, spin, and heat occurs in materials.

We use a variety of analytical and numerical tools to address the research questions above, depending on which method is the most appropriate for a particular research project. Some of our theoretical approaches include lattice models, quasiclassical Keldysh theory, Green function techniques, scattering theory, and Landau-Lifshitz-Gilbert phenomenology.

Key questions 

The main challenges that we are attempting to solve are related to the functional properties of materials and how they can be controlled or altered by combining different materials.For instance, is it possible to use magnetic materials to control when superconductivity appears and even enhance its properties? Can one use superconductors to generate, control, and detect transport of not only charge but also other quantum degrees of freedom such as spin, without any energy loss? Finally, we are interested in understanding how superconductivity is manifested in unusual solid-state systems, such as atomically thin materials.

For current activities, see QuSpin Annual Report 2025.

Theme and goal

The recent decades have seen the rise of modern information and communication technologies, largely based on the use of semiconductors in transistors and integrated electronic circuits. This era is sometimes referred to as the “silicon age“, highlighting the importance of the material silicon in this context. The properties of silicon are well understood on fundamental grounds. However, there are classes of materials whose physical behaviour is vastly more complex and less understood, including superconductors, magnets, and topological systems. In these „quantum materials“ the quantum-mechanical nature of the electrons and their mutual interactions come to the forefront and remain manifest over a wider range of energy and length scales. Researchers envision that proper control of these quantum effects and resolving some of their puzzles could enable new technologies beyond the silicon age. Understanding the physics of quantum materials is challenging, however, and involves the development and application of sophisticated experimental and theoretical techniques.

We use a method called spin- and angle-resolved photoelectron spectroscopy (spin-ARPES) to investigate magnetic and topological materials. Spin-ARPES is based on the photoelectric effect, i.e. the excitation of photoelectrons at a material surface upon irradiation with monochromatic light. The effect has long been known and constitutes one of the key observations that paved the way from classical electrodynamics to quantum mechanics. Use of modern spectrometers and light sources allows us to study the spatial, angular and spin distributions of photoemitted electrons as well as their dependence on energy and polarization of the exciting light, providing detailed information about electronic and magnetic properties. With this, our goal is to contribute to the discovery and to a refined microscopic understanding of quantum states in new and complex materials.

Key questions

Our primary focus lies on the investigation of electronic states with so-called topological properties which give rise to unusual spin textures in momentum space. We are interested in how topological properties and spin textures are related to or modified by ferromagnetic or antiferromagnetic order, specific crystalline symmetries, quantum confinement in atomically thin crystals and proximity coupling in heterostructures. Spin-ARPES allow us to directly address these points experimentally. Our experiments are performed in the laboratory at NTNU and at international synchrotron radiation facilities, such as PETRA III at DESY (Hamburg).

For current activities, see QuSpin Annual Report 2025.