Electric field modulation of spin transport.

Zucchetti C., Marchionni A., Bollani M., Grassi P., Ciccacci F., Finazzi M., Bottegoni F.
  Martedì 13/09   09:00 - 13:30   Aula D - Marianna Ciccone   II - Fisica della materia   Presentazione
The finite spin lifetime in solids is often considered a major hindrance for the development of spintronic devices. In this contribution, we show that this feature can instead be exploited to realize a scheme where spin transport is modulated at room temperature by a modest electric field. To prove this concept, we employ a nonlocal spin-injection/detection scheme that enables one to directly investigate drift-diffusive spin transport at room temperature with a device-oriented architecture. We show that a finite spin-diffusion length combined with the application of an electric field can be capitalized to manipulate spin accumulation. We find that applying an electric field $E$ = 24 ${V/cm}$ along a $40 \mu m-long$ path in germanium results in about one order of magnitude modulation of the spin-polarized electrons entering the detector. Moreover, in the best-case scenario, we directly image a spin-transport length of $40 \mu m.$ Comparable values in semiconductors have been predicted and observed only at cryogenic temperatures. Hence, our work demonstrates that electric fields can be exploited for guiding spins over macroscopic distances and for realizing room temperature modulation of spin accumulation.