Electric Field Regulates The Spin Transport And Photogalvanic Effect In Phthalocyanine Molecules

Compared with traditional semiconductor materials,organic molecular materials have the advantages of flexibility,weak spin-orbit coupling and long spin relaxation time.Molecular devices will play an important role in the miniaturization of spintronic devices in the future,the precise manipulation of the quantum state of a single molecule at the atomic scale and the controllable modulation of its physical properties have always been one of the most important frontier researches in condensed matter physics and its applications.The control of spin states at the molecular scale by magnetic methods often requires very strong magnetic fields,which restricts the integration of devices and the combination with traditional semiconductor technologies.It is one of the core issues in the field of molecular spintronics to explore the control of spin output signal in molecular devices by electric field and light,and to develop a new method of spin control.In this paper,molecular devices composed of one-dimensional gold nanowires as electrodes and metal phthalocyanine molecules as central regions are studied using the first-principles method combining the density functional theory(DFT)with the non-equilibrium Green's function(NEGF).The control of spin transport in molecular devices by means of gate voltage and photgalvanic effect is discussed.The main contents are as follows:1.Research on the properties of single phthalocyanine molecular spin field effect transistor: the spin transport properties of single chromium phthalocyanine molecular devices(CrPc)and single iron phthalocyanine molecular devices(FePc)and the regulation of gate voltage on the spin filtering effect(SFE)of the two were studied.It is found that FePc devices have excellent spin filtering effect,and CrPc is second.Based on a certain bias voltage,under the control of gate voltage,the SFE of FePc device remains above 90% and increases slightly;under the control of gate voltage,the SFE of CrPc increases by 60%.2.Study on photgalvanic effect in ferrophthalocyanine molecule: In ferrophthalocyanine molecular device,linearly polarized light with different energies is irradiated to the molecule,and it is found that the maximum photocurrent is excited when the light energy is 1.50 e V and 1.70 e V,and the photocurrent generated is spin-polarized.The magnitude of photocurrent satisfies the cosine relation with the polarization Angle of incident polarized light.It is found that due to the existence of iron atom in the center of phthalocyanine molecule,the molecule is magnetized,and the symmetry of mirror image and space inversion are destroyed,resulting in the photocurrent can be generated even without bias voltage.3.Properties of spin field effect transistor for dichrophthalocyanine molecular devices(Cr2Pc2): The spin transport properties and gate voltage regulation of SFE in the spin field effect transistor based on Cr2Pc2 molecule are studied under certain bias voltage.It is found that under the control of gate voltage,the Cr2Pc2 molecular device has better spin filtering effect,and the SFE of parallel Cr2Pc2 device increases by nearly 30% and has perfect spin filtering effect.The SFE of antiparallel devices increases by nearly 75%.The peak value of the reluctance of Cr2Pc2 device is about3200% under the control of gate voltage.