2008/06/27 by Enrico Perfetto, Gianluca Stefanucci, Michele Cini · 2 citations
Engineering · Physics and Astronomy · #Advancements in Semiconductor Devices and Circuit Design #Condensed matter physics #Electron #Ferromagnetism #Magnetic field #Magnetic properties of thin films #Magnetoresistance #Physics #Quantum and electron transport phenomena #Quantum dot #Quantum mechanics #Quantum tunnelling #Scattering #Spin (aerodynamics) #Spin polarization #Spin-flip #Spintronics #cond-mat.mes-hall
paper · pdf · doi:10.1103/physrevb.78.155301
11 pages, 13 eps figures
arxiv created 2008/06/27 · openalex publication_date 2008/10/01 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We study the effects of spin-flip scatterings on the time-dependent transport properties through a magnetic quantum dot attached to normal and ferromagnetic leads. The transient spin dynamics as well as the steady-state tunneling magnetoresistance (TMR) of the system are investigated. The absence of a definite spin-quantization axis requires the time propagation of two-component spinors. We present numerical results in which the electrodes are treated both as one-dimensional tight-binding wires and in the wide-band limit approximation. In the latter case we derive a transparent analytic formula for the spin-resolved current, and transient oscillations damped over different time scales are identified. We also show that in the presence of spin-flip scatterings the TMR can be inverted even for symmetrically coupled leads. For any given strength of the spin-flip coupling the TMR becomes negative provided the ferromagnetic polarization is larger than some critical value. Finally we show how the full knowledge of the transient response allows for enhancing the spin current by properly tuning the period of a pulsed bias.