In thermoelectricity,the inherent coupling between electrical conductivity and Seebeck coefficient represents a fundamental challenge in thermoelectric materials development.Herein,we present a unique pressure-tuning ...In thermoelectricity,the inherent coupling between electrical conductivity and Seebeck coefficient represents a fundamental challenge in thermoelectric materials development.Herein,we present a unique pressure-tuning strategy using compressible layered 2H-MoTe2,achieving an effective decoupling between the electrical conductivity and Seebeck coefficient.The applied pressure simultaneously induces two complementary effects:(1)bandgap reduction that moderately enhances carrier concentration to improve the electrical conductivity,and(2)band convergence that dramatically increases density-of-states effective mass to boost the Seebeck coefficient.This dual mechanism yields an extraordinary 18.5-fold enhancement in the average power factor.First-principles calculations and Boltzmann transport modeling precisely reproduce the experimental observations,validating this pressure-induced decoupling mechanism.The pressure-tuning mechanism provides a feasible and effective strategy for breaking through the optimization limits of the power factor,facilitating the design of high-performance thermoelectric materials.展开更多
We theoretically study nonlinear thermoelectric transport through a topological superconductor nanowire hosting Majorana bound states(MBSs) at its two ends, a system named as Majorana nanowire(MNW). We consider that t...We theoretically study nonlinear thermoelectric transport through a topological superconductor nanowire hosting Majorana bound states(MBSs) at its two ends, a system named as Majorana nanowire(MNW). We consider that the MNW is coupled to the left and right normal metallic leads subjected to either bias voltage or temperature gradient. We focus our attention on the sign change of nonlinear Seebeck and Peltier coefficients induced by mechanisms related to the MBSs, by which the possible existence of MBSs might be proved. Our results show that for a fixed temperature difference between the two leads, the sign of the nonlinear Seebeck coefficient(thermopower) can be reversed by changing the overlap amplitude between the MBSs or the system equilibrium temperature, which are similar to the cases in linear response regime. By optimizing the MBS–MBS interaction amplitude and system equilibrium temperature, we find that the temperature difference may also induce sign change of the nonlinear thermopower. For zero temperature difference and finite bias voltage, both the sign and magnitude of nonlinear Peltier coefficient can be adjusted by changing the bias voltage or overlap amplitude between the MBSs. In the presence of both bias voltage and temperature difference, we show that the electrical current at zero Fermi level and the states induced by overlap between the MBSs keep unchanged, regardless of the amplitude of temperature difference. We also find that the direction of the heat current driven by bias voltage may be changed by weak temperature difference.展开更多
Heat conduction in oxygen probe was analyzed by means of non-steady state method and measured using 'double probe' arrangement. The results showed that during the response process the thermal emf was decreased...Heat conduction in oxygen probe was analyzed by means of non-steady state method and measured using 'double probe' arrangement. The results showed that during the response process the thermal emf was decreased exponentially with the time and in case of low oxygen level the Seebeck coefficient and thermal conductivity of solid electrolyte agreed well with those in literatures.展开更多
Spin currents,which are excited in indium tin oxide(ITO)/yttrium iron garnet(YIG)by the methods of spin pumping and spin Seebeck effect,are investigated through the inverse spin Hall effect(ISHE).It is demonstrated th...Spin currents,which are excited in indium tin oxide(ITO)/yttrium iron garnet(YIG)by the methods of spin pumping and spin Seebeck effect,are investigated through the inverse spin Hall effect(ISHE).It is demonstrated that the ISHE voltage can be generated in ITO by spin pumping under both in-plane and out-of-plane magnetization configurations.Moreover,it is observed that the enhancement of spin Hall angle and interfacial spin mixing conductance can be achieved by an appropriate annealing process.However,the ISHE voltage is hardly seen in the presence of a longitudinal temperature gradient.The absence of the longitudinal spin Seebeck effect can be ascribed to the almost equal thermal conductivity of ITO and YIG and specific interface structure,or to the large negative temperature dependent spin mixing conductance.展开更多
基金supported by the Science and Technology Development Project of Jilin Province(Grant No.SKL202402004)the Program for the Development of Science and Technology of Jilin Province(Grant No.YDZJ202201ZYTS308)+1 种基金the Open Research Fund of State Key Laboratory of Inorganic Synthesis and Preparative Chemistry,Jilin University(Grant Nos.202216 and 2022-23)the National Natural Science Foundation of China(Grant No.12350410372)。
文摘In thermoelectricity,the inherent coupling between electrical conductivity and Seebeck coefficient represents a fundamental challenge in thermoelectric materials development.Herein,we present a unique pressure-tuning strategy using compressible layered 2H-MoTe2,achieving an effective decoupling between the electrical conductivity and Seebeck coefficient.The applied pressure simultaneously induces two complementary effects:(1)bandgap reduction that moderately enhances carrier concentration to improve the electrical conductivity,and(2)band convergence that dramatically increases density-of-states effective mass to boost the Seebeck coefficient.This dual mechanism yields an extraordinary 18.5-fold enhancement in the average power factor.First-principles calculations and Boltzmann transport modeling precisely reproduce the experimental observations,validating this pressure-induced decoupling mechanism.The pressure-tuning mechanism provides a feasible and effective strategy for breaking through the optimization limits of the power factor,facilitating the design of high-performance thermoelectric materials.
基金Project supported by the National Natural Science Foundation of China(Grant No.12264037)the Innovation Team of Colleges and Universities in Guangdong Province(Grant No.2021KCXTD040)+2 种基金Guangdong Province Education Department(Grant No.2023KTSCX174)the Key Laboratory of Guangdong Higher Education Institutes(Grant No.2023KSYS011)Science and Technology Bureau of Zhongshan(Grant No.2023B2035)。
文摘We theoretically study nonlinear thermoelectric transport through a topological superconductor nanowire hosting Majorana bound states(MBSs) at its two ends, a system named as Majorana nanowire(MNW). We consider that the MNW is coupled to the left and right normal metallic leads subjected to either bias voltage or temperature gradient. We focus our attention on the sign change of nonlinear Seebeck and Peltier coefficients induced by mechanisms related to the MBSs, by which the possible existence of MBSs might be proved. Our results show that for a fixed temperature difference between the two leads, the sign of the nonlinear Seebeck coefficient(thermopower) can be reversed by changing the overlap amplitude between the MBSs or the system equilibrium temperature, which are similar to the cases in linear response regime. By optimizing the MBS–MBS interaction amplitude and system equilibrium temperature, we find that the temperature difference may also induce sign change of the nonlinear thermopower. For zero temperature difference and finite bias voltage, both the sign and magnitude of nonlinear Peltier coefficient can be adjusted by changing the bias voltage or overlap amplitude between the MBSs. In the presence of both bias voltage and temperature difference, we show that the electrical current at zero Fermi level and the states induced by overlap between the MBSs keep unchanged, regardless of the amplitude of temperature difference. We also find that the direction of the heat current driven by bias voltage may be changed by weak temperature difference.
文摘Heat conduction in oxygen probe was analyzed by means of non-steady state method and measured using 'double probe' arrangement. The results showed that during the response process the thermal emf was decreased exponentially with the time and in case of low oxygen level the Seebeck coefficient and thermal conductivity of solid electrolyte agreed well with those in literatures.
基金Project supported by the National Key Basic Research Project of China(Grant No.2016YFA0300600)Chinese Academy of Sciences(Grant No.KJCX2-YW-W24)+1 种基金the Young Scientists Fund of the National Natural Science Foundation of China(Grant No.11604375)the Laboratory of Microfabrication of Institute of Physics,Chinese Academy of Sciences
文摘Spin currents,which are excited in indium tin oxide(ITO)/yttrium iron garnet(YIG)by the methods of spin pumping and spin Seebeck effect,are investigated through the inverse spin Hall effect(ISHE).It is demonstrated that the ISHE voltage can be generated in ITO by spin pumping under both in-plane and out-of-plane magnetization configurations.Moreover,it is observed that the enhancement of spin Hall angle and interfacial spin mixing conductance can be achieved by an appropriate annealing process.However,the ISHE voltage is hardly seen in the presence of a longitudinal temperature gradient.The absence of the longitudinal spin Seebeck effect can be ascribed to the almost equal thermal conductivity of ITO and YIG and specific interface structure,or to the large negative temperature dependent spin mixing conductance.
