Theoretical Studies On The Spin Transport Properties In The Protein-like Organic Molecules

Molecular spintronics,which manipulates electron spin transport through organic molecules,involves multidisciplinary filed,has been receiving much attention among the physics,chemistry,and biology communities,because spin transport has huge potential applications in storage and transfer information.Recent experiments found double stranded protein-like molecules are significant spin filters,which attracts strong interests of a lot of researchers to study chiral-induced spin selectivity.In the thesis,we report theoretical studies on the spin-polarized electron transport through the single-helical molecules connected with two normal metallic leads.Using Hamiltonian model and the Landauer-Büttiker function method,we propose a single-helical protein-like molecule model of chain and a single-helical protein-like molecule model of a quantum ring with an embedded protein-like single-helical molecule.the theoretical analysis was conducted to explain the factors affecting the spin transport in simple chain single-stranded protein-like organic molecules,As well as the spin transport in quantum circular protein-like organic molecules and their thermoelectric and thermo-spin conditions.First of all,we simulate the spin transport properties of single helix molecules.Based on the Hamiltonian and the Landauer-Büttiker function method,a molecular structure model of single-stranded helix protein-like was constructed.The effect of external factors(i.e.the size,direction and decoherence strength of the gate voltage)beacause of external electric field and experimental environment and the internal factors(i.e.molecular length N,stacking distance,twist angle)beacause of intrinsic electric field and special helical structure of single helical protein molecule on the spin polarization effect of single helical protein molecule are mainly studied.As a result,we have studied the effect of electron spin polarization by single helix protein produced by length of the single helix protein molecules and the special helical structure of the molecule.The conclusion shows that the spin filtering capability of the single helix protein molecule can be improved,by choosing the appropriate length of the single helical protein molecule and regulating the molecular helix structure.The optimal structural parameters for the maximal spin polarization are analyzed.Our results show that the dephasing term is an important factor to enhance the spin polarization,in addition to the intrinsic parameters of the single-helical molecule.This work can be helpful in optimizing the spin polarization in the protein-like single-helical molecules.Secondly,the spin-polarized transport properties in a circular,protein-like SH molecule were then simulated.1.Quantum circular protein-like in organic molecules in the case of spin transport From the images we can observe that quantum interference between arms enhances spin polarization during electron transport In addition,spin polarization,including polarization intensity and direction,can be effectively adjusted when a local flux is introduced into the structure.Next spin polarization is evident when a finite bias voltage is applied between leads in the presence of a suitable magnetic flux.These results imply that quantum interference modified by local magnetic flux is an effective mechanism to enhance the spin polarization of SH molecules.This work helps to enhance the electron-spin spin polarization in the mesoscopic setup with SH molecules.2.The thermodynamic and thermo-rotational properties of protein-like-based organic molecules in the quantum ring,we observe that the thermoelectric and thermo-spin effects through this ring are all significant.In addition,it is proved that the thermal rotation effect can be effectively improved when a partial flux is introduced.Therefore,this work provides a feasible solution to enhance the thermoelectric and thermo-spin effect in a system.Based on this result,we believe.this structure can be used as an effective thermoelectric generator or temperature gradient sensor.In addition,this structure is a promising candidate for thermal spin generators because it produces a significant spin current with an adjustable polarization direction by non-magnetic means.The main highlights of this paper are as follows:protein-like organic molecular materials are one of the best candidates for spintronic devices.The study of their electronic and spin transport properties is a new field,and the research in this area is still in its infancy.The research in this paper can promote and enrich this field,and provide theoretical basis and find potential application value by simulating computationally electronic and spintronic devices in protein-like-based organic molecular systems from the microscopic point of view.