spinstromen

Spinstromen, a Dutch term that translates to spin currents, refer to the transport of spin angular momentum in solid-state systems. Unlike ordinary electric currents, which carry electric charge, spinstromen convey information about the spin state of carriers, and can exist with or without net charge flow. They may be carried by moving spin-polarized electrons in metals and semiconductors or by collective excitations such as magnons in magnetic insulators. In theoretical descriptions, spin currents are often represented by a spin-current density, a tensor that describes the flow of spin polarization components.

Spinstromen are a central concept in spintronics, a field that seeks to exploit electron spin for information processing and storage. In materials with significant spin-orbit coupling, spin is not strictly conserved, which allows the generation and manipulation of spin currents even in the absence of large charge currents. Common generation mechanisms include electrical spin injection from a ferromagnetic contact into a nonmagnetic material, the spin Hall effect where a transverse spin current arises from a longitudinal charge current, and spin pumping from a dynamically driven ferromagnet. Thermally driven effects, such as the spin Seebeck effect, and magnonic transport in insulating magnets also contribute to spinstromen.

Materials and devices often used to create and detect spinstromen include heavy metals with strong spin-orbit coupling (such as platinum, tantalum, and tungsten) and ferromagnet–nonmagnet heterostructures, as well as magnonic insulators. Detection methods encompass nonlocal electrical measurements and inverse spin Hall voltages, among others.

Applications of spinstromen span nonvolatile memory (such as MRAM), spin-based logic, and low-power interconnects. The study of spinstromen also raises fundamental questions about angular-momentum conservation under spin-orbit interactions and continues to drive experimental and theoretical development in spintronics.