Electron Spin Resonance and Related Phenomena in Low-Dimensional Structures

The spin degree-of-freedom is o?ering a wide range of intriguing oppor- nities both in fundamental as well as in applied solid-state physics. When combined with the rich and fertile physics of low-dimensional semicondu- ingstructuresandwiththepossibilitytochange,forexample,carrierdensity, electric ?elds or coupling to other quantum systems in a controlled way, an extremely exciting and interesting research ?eld is opened. Most comm- cial electronic devices are based on spin-independent charge transport. In the last two decades, however, scientists have been focusing on the ambitious objective of exploiting the spin degree-of-freedom of the electron to achieve novel functionalities. Ferromagnetic semiconductors, spin transistors, sing- spin manipulations or spin-torque MRAMs (magnetoresistive random access memories) are some of the hot topics. The importance of spin phenomena for new applications was recognized by the Royal Swedish Academy of S- ences by awarding the 2007 Nobel Prize in Physics jointly to Albert Fert and Peter Grun ¨ berg “for the discovery of giant magnetoresistance”. This - fect originates from spin-dependent scattering phenomena in a two-terminal ferromagnetic–paramagnetic–ferromagnetic junction leading to a new type of magnetic memory. The Hall e?ect and its applications remain fertile - search areas. The spin Hall e?ect, in analogy with the conventional Hall e?ect, occurs in paramagnetic systems as a result of spin-orbit interaction.