Effect of the magnetic domain structure in the ferromagnetic contact on spin accumulation in silicon.

We show a marked effect of magnetic domain structure in an epitaxial CoFe contact on spin accumulation signals in Si devices detected by three-terminal Hanle effect measurements. Experimental results indicate that magnetic domain structures cause large discrepancies in the estimation of spin lifetime and bias-current dependence of the spin accumulation signal. By introducing the domain walls in CoFe contact, spin accumulation signals are reduced, which is caused by the lateral spin transport in the Si channel. Thus, to understand precisely the physical properties of Si spintronic devices, it is important to take into account the control of magnetic domain structure in the contacts. [ABSTRACT FROM AUTHOR]