Abstract
We propose two new approaches for regulating spin polarization and spin inversion in a conducting junction within a tight-binding framework based on wave-guide theory. The system comprises a magnetic quantum ring with finite modulation in site potential is coupled to two non-magnetic electrodes. Due to close proximity an additional tunneling is established between the electrodes which regulates electronic transmission significantly. At the same time the phase associated with site potential, which can be tuned externally yields controlled transmission probabilities. Our results are valid for a wide range of parameter values which demonstrates the robustness of our proposition. We strongly believe that the proposed model can be realized in the laboratory.
Highlights
We propose two new approaches for regulating spin polarization and spin inversion in a conducting junction within a tight-binding framework based on wave-guide theory
We would like to state that though the results presented in Fig. 11 are computed for a specific value of θ, almost similar kind of physical picture is obtained for other values of θ
A complete sign reversal of spin polarization (i.e., P = +1 to P = −1 and vice versa) takes place by changing any one of the two controlling parameters
Summary
The coefficients An,σ, Bn,σ, and Cn,σ correspond to the amplitude for an electron having spin σ (↑ or ↓) at the n th site of the source, drain, and i th site of the ring, respectively. With this wave function we can write a set of coupled linear equations from the time-independent Schrödinger equation H|ψ〉 = EI|ψ〉 (I being the (2 × 2) identity matrix) as:. Assuming a plane wave incidence for up spin electrons with unit amplitude, we can write the amplitudes as: An = eik(n+1r↑)a↓e+−ikr(↑n↑+e−1)iak(n+1)a and Bn = tt↑↑↑↓eeiikknnaa , where a being the lattice spacing and k is the wave vector associated with the energy E.
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