Shot noise at spin - dependent hopping in tunnel junctions with ferromagnetic electrodes

Submitted for the MAR17 Meeting of The American Physical Society Shot noise at spin-dependent hopping in tunnel junctions with ferromagnetic electrodes VIKTOR SVERDLOV, SIEGFRIED SELBERHERR, Institute for Microelectronics, TU Wien — Although resistance modulation with magnetic field due to spin-dependent resonant tunneling [1] is likely responsible for a larger signal than expected from spin accumulation measured within a three-terminal spin injection setup [2], the reason for the discrepancy is still under scrutiny [3]. An additional characteristic capable to distinguish between spin-dependent trap-assisted tunneling and spin accumulation due to direct tunneling is needed. We calculate the shot noise at spin-dependent hopping and demonstrate that, due to the Pauli spin blockade in a magnetic field parallel to the magnetization of the ferromagnetic contacts, the Fano factor is significantly enhanced above its value at direct tunneling. Only in this case the spin-dependent tunneling rates are determined by the two spinup and spin-down eigenvalues of a 4×4 non-symmetric transition matrix, while in the general case all four eigenvalues contribute into the transition rate. This explains the discrepancy between [1] and [4], where only the two eigenstates are considered. 1.Y.Song and H.Dery, PRL 113, 047205 (2014). 2.R.Jansen, Nature Materials 11, 400 (2012). 3.A.Spiesser et al., Appl.Phys.Express 9, 103001 (2016). 4.Z.Yue et al., PRB 91, 195316 (2015). Viktor Sverdlov Institute for Microelectronics, TU Wien Date submitted: 10 Nov 2016 Electronic form version 1.4