Spin injection and accumulation in mesoscopic metal device structures

摘要

There have been several recent experiments involving spin injection and accumulation in mesoscopic metal samples, using lateral spin valve structures. The results have been interesting from the perspectives of both fundamental physics and applications. The resistance change associated with spin accumulation, ΔR, has been predicted to scale inversely with sample volume and this inverse scaling has been observed over ten decades. A value of ΔR = 1 Ohm has been reported, at room temperature, in a thin film Al wire structure with transverse dimensions of roughly 100 nm. High values of AR have been observed in samples characterized by electrode interface resistances that vary by 6 decades. Results are discussed within the framework of Johnson-Silsbee theory, and factors that limit inverse scaling are identified. Lateral spin valves with dimensions of tens of nm may be competitive for device applications. Structures with AR of order 1 Ohm are superior to CPP spin valves of comparable dimensions. Prospects for improved performance, the plausibility of a lateral spin valve with output levels of 10 Ohms and output impedance of 50 Ohms, and relevance to hard drive read heads and integrated nonvolatile random access memory applications are discussed.