With the rapidly increasing integration density and power density in nanoscale electronic devices,the thermal management concerning heat generation and energy harvesting becomes quite crucial.Since phonon is the major...With the rapidly increasing integration density and power density in nanoscale electronic devices,the thermal management concerning heat generation and energy harvesting becomes quite crucial.Since phonon is the major heat carrier in semiconductors,thermal transport due to phonons in mesoscopic systems has attracted much attention.In quantum transport studies,the nonequilibrium Green’s function(NEGF)method is a versatile and powerful tool that has been developed for several decades.In this review,we will discuss theoretical investigations of thermal transport using the NEGF approach from two aspects.For the aspect of phonon transport,the phonon NEGF method is briefly introduced and its applications on thermal transport in mesoscopic systems including one-dimensional atomic chains,multi-terminal systems,and transient phonon transport are discussed.For the aspect of thermoelectric transport,the caloritronic effects in which the charge,spin,and valley degrees of freedom are manipulated by the temperature gradient are discussed.The time-dependent thermoelectric behavior is also presented in the transient regime within the partitioned scheme based on the NEGF method.展开更多
First-principles calculations were performed to explore the spin-resolved electronic and thermoelectric transport properties of a series of graphene-nanoribbon-based nanojunctions. By flipping the mag- netic moments i...First-principles calculations were performed to explore the spin-resolved electronic and thermoelectric transport properties of a series of graphene-nanoribbon-based nanojunctions. By flipping the mag- netic moments in graphene leads from parallel to antiparallei, very large tunneling magnetoresistance can be obtained under different gate voltages for all the structures. Spin-resolved alternating-current conductance increases versus frequency for the short nanojunctions but decreases for the long nano- junctions. With increasing junction length, the behavior of the junctions changes from capacitive-like to inductive-like. Because of the opposite signs of spin-up thermopower and spin-down thermopower near the Fermi level, pure spin currents can be obtained and large figures of merit can be achieved by adjusting the gate voltage and chemical potential for all the nanojunctions.展开更多
基金the National Natural Science Foundation of China(Grant Nos.12074190,11975125,11890703,and 11874221).
文摘With the rapidly increasing integration density and power density in nanoscale electronic devices,the thermal management concerning heat generation and energy harvesting becomes quite crucial.Since phonon is the major heat carrier in semiconductors,thermal transport due to phonons in mesoscopic systems has attracted much attention.In quantum transport studies,the nonequilibrium Green’s function(NEGF)method is a versatile and powerful tool that has been developed for several decades.In this review,we will discuss theoretical investigations of thermal transport using the NEGF approach from two aspects.For the aspect of phonon transport,the phonon NEGF method is briefly introduced and its applications on thermal transport in mesoscopic systems including one-dimensional atomic chains,multi-terminal systems,and transient phonon transport are discussed.For the aspect of thermoelectric transport,the caloritronic effects in which the charge,spin,and valley degrees of freedom are manipulated by the temperature gradient are discussed.The time-dependent thermoelectric behavior is also presented in the transient regime within the partitioned scheme based on the NEGF method.
基金This work was financially supported by grant from the National Natural Science Foundation of China （Grant Nos. 11304205 and 11404273） and Shenzhen Natural Science Foundation （No. JCYJ20130326111836781）.
文摘First-principles calculations were performed to explore the spin-resolved electronic and thermoelectric transport properties of a series of graphene-nanoribbon-based nanojunctions. By flipping the mag- netic moments in graphene leads from parallel to antiparallei, very large tunneling magnetoresistance can be obtained under different gate voltages for all the structures. Spin-resolved alternating-current conductance increases versus frequency for the short nanojunctions but decreases for the long nano- junctions. With increasing junction length, the behavior of the junctions changes from capacitive-like to inductive-like. Because of the opposite signs of spin-up thermopower and spin-down thermopower near the Fermi level, pure spin currents can be obtained and large figures of merit can be achieved by adjusting the gate voltage and chemical potential for all the nanojunctions.
