Incoherent spin-polarized transport and spin accumulation in ferromagnetic semiconductor/superconductor/ferromagnetic semiconductor junctionsY. C. Tao1 and J. G. Hu2
1 Department of Physics, Nanjing Normal University - Nanjing 210097, PRC
2 Department of Physics, Yangzhou University - Yangzhou 225002, PRC
received 9 April 2007; accepted in final form 5 June 2007; published July 2007
published online 2 July 2007
Taking into account the Andreev reflection and spatial variation of the order para- meter in the superconductor (SC), we study the incoherent spin polarized transport in a ferromagnetic semiconductor (FS)/SC/FS structure. It is found that the variations of the nonequilibrium spin accumulation in the SC originated by the tunneling current in the antiferromagnetic alignment of the magnetizations and differential conductance of the heavy and light holes in either ferromagentic or antiferromagnetic alignment with bias voltage, strongly depend on not only the mismatches in the effective mass and Fermi velocity between the FS and SC but also on the strengths of the potential scattering at the interfaces. It is also shown that tunneling magnetoresistance (TMR) is very weakly dependent on the bias voltage and the strengths of potential scattering at the interfaces, and this provides a new method for measuring the spin polarization in the FS.
72.25.Dc - Spin polarized transport in semiconductors.
72.25.Mk - Spin transport through interfaces.
75.50.Pp - Magnetic semiconductors.
© Europhysics Letters Association 2007