The generation and measurement of spin currents, one of the central goals of spintronics, can be realised in different ways:
- through the transport of electron spins in metals
- through the motion of Bloch or Neel walls or topological structures such as vortices and skyrmions
- through the transmission of spin waves in ferromagnets.
INRiM studies various spintronic systems:
- Heterostructures containing magnetic and non-magnetic layers with significant spin-orbit effects (e.g. Co / Pt and Ta / CoFeB). These structures exhibit inversion symmetry breaking and are characterised by the Dzyaloshinskii-Moriya (DMI) interaction, which acts as an anisotropic exchange interaction between adjacent spins. This interaction generates stable magnetic configurations, such as domain walls with a fixed chirality and skyrmions and small magnetic vortices characterised by high stability. INRIM is actively researching the determination of the DMI constant, which is crucial for future spintronic applications.
- Magnetic tunnel junctions, already widely applied in hard disk read heads and magnetic random access memories (MRAM) devices. Such systems are based on the spin-transfer-torque effect caused by a spin current undergoing a tunnel effect between two magnetic layers separated by an insulating layer. INRIM studies magnetisation dynamics (e.g. magnetic vortices) as a function of important influencing parameters such as defects or heat.
- Bilayers consisting of a metal layer with a strong spin-hall effect (e.g. Pt) and an insulating ferromagnet (e.g. YIG). In these systems, spin current can be generated in one of the two layers and transmitted into the other through the interface, giving rise to a variety of new physical effects. INRIM is active in the experimental and theoretical examination of Seebeck spin, Peltier spin, spin pumping and spin Hall torque effects, which emerge in these configurations and represent promising spintronic devices.
- Magnetic films (e.g. Permalloy, YIG) for ferromagnetic resonance (FMR) and spin-wave measurements in the time and frequency domain to understand the generation and propagation of spin currents.