The Thermoelectric Response And Steady-state TAMR In Single Molecule Magnet

Single molecule magnets(SMM)with large spin(S>1/2)and anisotropy not only show the various macroscopic quantum effects,but also the quantum transport experiments and theory show that the SMM will be the good candidate material to realize spintronics device.Therefore,the quantum transport through a SMM tunneling junction and quantum manipulation of the SMM magnetization attracted considerable attention.In this paper,we consider a SMM tunneling junction,which is made up of a SMM,a ferromagnetic electrode(F)and a metal electrode(N),and study the temperature gradient driven thermoelectric transport of the system and related effect.The main research content is as follows:(1)The thermoelectric response of SMM's magnetization is studied in the F-SMM-N tunneling junction.When the temperature difference between two electrodes is more than the critical value,the SMM magnetization can flip under the control of gate voltage.The fliping time is related to the temperature difference,the gate voltage,spin exchange coupling and other system parameters.The flip arises from the spin torque effect and the thermal spin-polarized currents induced by temperature difference and gate voltage.(2)We study the tunneling anisotropic magnetresistance(TAMR)in a non-collinear F-SMM-N tunneling junction.The magnetization of electrode and the large spin of SMM are non-collinear,meaning that there is an angle?between them.When the gate voltage is lower than its critical value,the value of TAMR appears a sudden change at?=?/2,and the amplitude of that sudden change increases with the temperature gradient and exchange coupling strength increasing.The sudden change of TAMR can be explained by the sudden change of molecular state occupy probability which results in the sudden change of tunneling current.(3)The spin current in F-SMM-F tunneling junction is studied.Under the appropriate temperature difference and gate voltage driving,F-SMM-F tunneling junction can produce spin-polarized current and pure spin current.When the magnetic field is applied the spin current increases.When antiferrmagnetic exchange coupling interaction occurs between electronic spin and the large spin of SMM,spin-up and spin-down currents are completely separated,which can produce 100%spin polarization current.