Spin Dependent Transport through Driven Magnetic System with Aubry-Andre-Harper Modulation

Abstract

In this work, we put forward a prescription of achieving spin selective electron transfer by means of light irradiation through a tight-binding (TB) magnetic chain whose site energies are modulated in the form of well known Aubry–Andre–Harper (AAH) model. The interaction of itinerant electrons with local magnetic moments in the magnetic system provides a misalignment between up and down spin channels which leads to a finite spin polarization (SP) upon locating the Fermi energy in a suitable energy zone. Both the energy channels are significantly affected by the irradiation which is directly reflected in degree of spin polarization as well as in its phase. We include the irradiation effect through Floquet ansatz and compute spin polarization coefficient by evaluating transmission probabilities using Green’s function prescription. Our analysis can be utilized to investigate spin dependent transport phenomena in any driven magnetic system with quasiperiodic modulations.

Possible Routes to Obtain Enhanced Magnetoresistance in a Driven Quantum Heterostructure with a Quasi-Periodic Spacer

“…There are two fundamental reasons for choosing this limiting condition. First, the Floquet bands are almost decoupled to each other, and thus, only the lowest order band contributes, i.e., [ 19 , 60 , 61 ]. Second, it is well-known that a -dimensional driven quantum system is equivalent to a -dimensional undriven quantum system.…”

“… is the fermionic creation (annihilation) operator for the n th site and their components obey anticommutation relation. The first term of Equation ( 2 ) denotes the on-site energy of magnetic chains in the presence of a spin-flip scattering mechanism [ 18 , 60 , 61 ] between the magnetic moments of the n th site and the incoming electron, and consequently, the potential profiles of the electrons belonging to two spin states become separated. is the potential energy at the n th site without any kind of interaction term.…”

“…It is straightforward to understand that, if the magnetization of the free layer is kept parallel to the fixed one, resistance becomes very low due to low scattering rates, and an antiparallel orientation suggests a high scattering rate, yielding a large resistance. Now, this spin-dependent transport [ 32 , 55 , 60 , 61 ] behavior can be tuned externally by modifying the characteristics of NM spacer and ferromagnetic layers. The site energies of the NM spacer is altered by cosine modulation following the AAH form [ 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 ], whereas the hopping parameter in ferromagnetic chains is rearranged by Floquet–Bloch anstaz [ 60 , 74 , 75 , 76 , 77 , 78 , 79 ] within a minimal coupling scheme due to light irradiation on them.…”

Localization Properties of a Quasiperiodic Ladder under Physical Gain and Loss: Tuning of Critical Points, Mixed-Phase Zone and Mobility Edge

“…The situation becomes very interesting when a correlation is imposed among the site energies. There exist many examples of correlated disordered systems that are widely used to study localization phenomena, and among them, the most notable system is probably the Aubry-André-Harper (AAH) [7][8][9][10][11][12][13][14][15][16][17] where site energies are correlated in the cosine form. Unlike in the 1D random disordered system, a 1D AAH chain provides a finite critical point of phase transition, described by the relation W c = 2t (t being the nearest-neighbor hopping (NNH) strength) [8,[18][19][20].…”

Molecular Electronics

“…This special issue aims at showcasing some of the many facets of research in molecular electronics and surveying the latest advances in the field. It contains seven studies, including five research papers [1][2][3][4][5] and two reviews [6,7], which span different areas of the field from both a theoretical and experimental perspective.…”