Perpendicular optical reversal of the linear dichroism transition has promising applications in polarization-sensitive optoelectronic devices. We perform a systematical study on the in-plane optical anisotropy of quas...Perpendicular optical reversal of the linear dichroism transition has promising applications in polarization-sensitive optoelectronic devices. We perform a systematical study on the in-plane optical anisotropy of quasi-one-dimensional PdBr_(2) by using combined measurements of the angle-resolved polarized Raman spectroscopy(ARPRS) and anisotropic optical absorption spectrum. The analyses of ARPRS data validate the anisotropic Raman properties of the PdBr_(2) flake.And anisotropic optical absorption spectrum of PdBr_(2) nanoflake demonstrates distinct optical linear dichroism reversal. Photodetector constructed by PdBr_(2) nanowire exhibits high responsivity of 747 A·W^(-1) and specific detectivity of 5.8×10^(12) Jones. And the photodetector demonstrates prominent polarization-sensitive photoresponsivity under 405-nm light irradiation with large photocurrent anisotropy ratio of 1.56, which is superior to those of most of previously reported quasi-one-dimensional counterparts. Our study offers fundamental insights into the strong optical anisotropy exhibited by PdBr_(2), establishing it as a promising candidate for miniaturization and integration trends of polarization-related applications.展开更多
Group IV element Pb has been selected as the dopant to dope at the Sr site of Sr_(2)IrO_(4). It is exciting to find that the single-phase crystal structure could be maintained with a high Pb doping level of up to x=0....Group IV element Pb has been selected as the dopant to dope at the Sr site of Sr_(2)IrO_(4). It is exciting to find that the single-phase crystal structure could be maintained with a high Pb doping level of up to x=0.3 in Sr_(2-x)Pb_(x)IrO_(4). The mapping data obtained from energy-dispersive x-ray spectroscopy analyses give solid evidence that the Pb ions are uniformly distributed in the Sr_(2)IrO_(4) matrix. The incorporation of Pb leads to a moderate depression of the canted antiferromagnetic ordering state. The electrical conductivity could be greatly enhanced when the Pb doping content is higher than x=0.2.The present results give a fresh material base to explore new physics in doped Sr_(2)IrO_(4) systems.展开更多
The continuing demand for new optoelectronic devices drives researchers to seek new materials suitable for photodetector applications.Recently,ternary compound semiconductors have entered researchers’field of vision,...The continuing demand for new optoelectronic devices drives researchers to seek new materials suitable for photodetector applications.Recently,ternary compound semiconductors have entered researchers’field of vision,among which chalcohalides have attracted special interest because of their rich properties and unique crystal structure consisting of atom chains and inter-chain van der Waals gaps.We have synthesized high-quality BiSeI single crystals with[110]-plane orientation and fabricated a photodetector.The optoelectronic measurements show a pronounced photocurrent signal with outstanding technical parameters,namely high responsivity(3.2 A/W),specific detectivity(7×10^(10) Jones)and external quantum efficiency(622%)for λ=635 nm,V_(ds)=0.1 V and P_(opt)=0.23 mW/cm^(2).The high performance of BiSeI photodetector and its layer structure make it a promising candidate for low-dimensional optoelectronic applications.展开更多
Non-stoiehiometry effect on the extreme magnetoresistanee is systematically investigated for the Weyl semimetal WTe2. Magnetoresistance and Hall resistivity are measured for the as-grown samples with a slight differen...Non-stoiehiometry effect on the extreme magnetoresistanee is systematically investigated for the Weyl semimetal WTe2. Magnetoresistance and Hall resistivity are measured for the as-grown samples with a slight difference in Te vacancies and the annealed samples with increased Te vacancies. The fits to a two-band model show that the magnetoresistanee is strongly dependent on the residual resistivity ratio （i.e., the degree of non-stoichiometry）, which is eventually understood in terms of electron doping that not only breaks the balance between electron-type and hole-type carrier densities, but also reduces the average carrier mobility. Thus the compensation effect and ultrahigh mobility are probably the main driving force of the extreme magnetoresistance in WTe2.展开更多
La（O,F）BiSe2 is a layered superconductor and has the same crystal structure with La（O,F）BiS2. We investigate the electronic structure of La（O,F）BiSe2 using the angle-resolved photoemission spectroscopy. Two elec...La（O,F）BiSe2 is a layered superconductor and has the same crystal structure with La（O,F）BiS2. We investigate the electronic structure of La（O,F）BiSe2 using the angle-resolved photoemission spectroscopy. Two electron-like Fermi surfaces around X（π, 0） are observed, corresponding to the electron doping of 0.23 per Bi site. We clearly resolve anisotropic band splitting along both Г-X and M-X due to the cooperative effects of large spin-orbit coupling and interlayer coupling. Moreover, we observe an almost non-dispersive electronic state around -0.2 eV between the electron-like bands. This state vanishes after in-situ K evaporation, indicating that it could be the localized surface state caused by defects on the cleaved surface.展开更多
We measure the current–voltage（I–V） characteristics for the single crystal of Tl0.4K0.41Fe1.71Se2 with the superconducting transition temperature（TC） around 30.5 K, under a 10 T magnetic field applied perpendicu...We measure the current–voltage（I–V） characteristics for the single crystal of Tl0.4K0.41Fe1.71Se2 with the superconducting transition temperature（TC） around 30.5 K, under a 10 T magnetic field applied perpendicular and parallel to the ab plane. We find that the shapes of the I–V isotherms are very different from the description by the vortex-glass（VG） model.Combining theoretical calculations and analysis of the ρH⊥ab–T and ρH ab–T data, we give an explicit discussion over the suitability of the VG model for the A0.8Fe2Se2 superconductors, and point out the possibility of the material acting as a convenient platform for re-examination and further study of the complex vortex behaviors in the layered superconductors.展开更多
The influence of Gd doping at La-site on the electrical transport properties and the colossal magnetoresistance of La0.7-xGdxSr0.3MnO3 (x = 0.00, 0.10, 0.15, 0.20, 0.30, 0.40, 0.50, 0.60, and 0.70) is studied. The exp...The influence of Gd doping at La-site on the electrical transport properties and the colossal magnetoresistance of La0.7-xGdxSr0.3MnO3 (x = 0.00, 0.10, 0.15, 0.20, 0.30, 0.40, 0.50, 0.60, and 0.70) is studied. The experimental results indicate that the transport properties exhibit abnormal behavior under high doping condition. For x = 0.50, we find that a transition from metal to insulator occurs after the occurrence of insulator-metal transition near Tc, which seldom occurs in ABO3 structure. For samples x = 0.60 and 0.70, it exhibits insulator behavior far above Tc. These abnormal behaviors are attributed to different magnetic background, i.e. the system undergoes a transition from long range ferromagnetic order to the cluster-spin glass state and further to antiferromagnetic order.展开更多
基金supported by the Scientific Research Grant of Hefei Science Center of Chinese Academy of Sciences(2015SRG-HSC025)National Natural Science Foundation of China(U1532267,11504379)~~
基金Project supported by the National Key Research and Development Program of China (Grant Nos. 2022YFA1403203 and 2021YFA1600201)the National Natural Science Foundation of China (Grant No. 12274414)the Basic Research Program of the Chinese Academy of Sciences Based on Major Scientific Infrastructures (Contract No. JZHKYPT-2021-08)。
文摘Perpendicular optical reversal of the linear dichroism transition has promising applications in polarization-sensitive optoelectronic devices. We perform a systematical study on the in-plane optical anisotropy of quasi-one-dimensional PdBr_(2) by using combined measurements of the angle-resolved polarized Raman spectroscopy(ARPRS) and anisotropic optical absorption spectrum. The analyses of ARPRS data validate the anisotropic Raman properties of the PdBr_(2) flake.And anisotropic optical absorption spectrum of PdBr_(2) nanoflake demonstrates distinct optical linear dichroism reversal. Photodetector constructed by PdBr_(2) nanowire exhibits high responsivity of 747 A·W^(-1) and specific detectivity of 5.8×10^(12) Jones. And the photodetector demonstrates prominent polarization-sensitive photoresponsivity under 405-nm light irradiation with large photocurrent anisotropy ratio of 1.56, which is superior to those of most of previously reported quasi-one-dimensional counterparts. Our study offers fundamental insights into the strong optical anisotropy exhibited by PdBr_(2), establishing it as a promising candidate for miniaturization and integration trends of polarization-related applications.
基金Project supported by the National Key R&D Program of China (Grant Nos.2022YFA1403203 and 2021YFA1600201)the National Natural Science Foundation of China (Grant Nos.11974356 and 12274414)+1 种基金the Joint Funds of the National Natural Science Foundation of Chinathe Chinese Academy of Sciences Large-Scale Scientific Facility (Grant No.U1932216)。
文摘Group IV element Pb has been selected as the dopant to dope at the Sr site of Sr_(2)IrO_(4). It is exciting to find that the single-phase crystal structure could be maintained with a high Pb doping level of up to x=0.3 in Sr_(2-x)Pb_(x)IrO_(4). The mapping data obtained from energy-dispersive x-ray spectroscopy analyses give solid evidence that the Pb ions are uniformly distributed in the Sr_(2)IrO_(4) matrix. The incorporation of Pb leads to a moderate depression of the canted antiferromagnetic ordering state. The electrical conductivity could be greatly enhanced when the Pb doping content is higher than x=0.2.The present results give a fresh material base to explore new physics in doped Sr_(2)IrO_(4) systems.
基金Supported by the National Key Research and Development Program of China(Grant No.2016YFA0300404)the National Natural Science Foundation of China(Grant No.11874363,11974356,and U1932216)the Collaborative Innovation Program of Hefei Science Center,CAS(Grant No.2019HSC-CIP002)。
文摘The continuing demand for new optoelectronic devices drives researchers to seek new materials suitable for photodetector applications.Recently,ternary compound semiconductors have entered researchers’field of vision,among which chalcohalides have attracted special interest because of their rich properties and unique crystal structure consisting of atom chains and inter-chain van der Waals gaps.We have synthesized high-quality BiSeI single crystals with[110]-plane orientation and fabricated a photodetector.The optoelectronic measurements show a pronounced photocurrent signal with outstanding technical parameters,namely high responsivity(3.2 A/W),specific detectivity(7×10^(10) Jones)and external quantum efficiency(622%)for λ=635 nm,V_(ds)=0.1 V and P_(opt)=0.23 mW/cm^(2).The high performance of BiSeI photodetector and its layer structure make it a promising candidate for low-dimensional optoelectronic applications.
基金Supported by the National Key R&D Program of China under Grant Nos 2016YFA0300404 and 2017YFA0403600the National Natural Science Foundation of China under Grant Nos 51603207,U1532267,11574288 and 11674327the Natural Science Foundation of Anhui Province under Grant No 1708085MA08
文摘Non-stoiehiometry effect on the extreme magnetoresistanee is systematically investigated for the Weyl semimetal WTe2. Magnetoresistance and Hall resistivity are measured for the as-grown samples with a slight difference in Te vacancies and the annealed samples with increased Te vacancies. The fits to a two-band model show that the magnetoresistanee is strongly dependent on the residual resistivity ratio （i.e., the degree of non-stoichiometry）, which is eventually understood in terms of electron doping that not only breaks the balance between electron-type and hole-type carrier densities, but also reduces the average carrier mobility. Thus the compensation effect and ultrahigh mobility are probably the main driving force of the extreme magnetoresistance in WTe2.
基金Supported by the National Basic Research Program of China under Grant Nos 2015CB921300,2013CB921700 and 2016YFA0300404the National Natural Science Foundation of China under Grant Nos 11474340,11234014,U1532267 and 11674327the Chinese Academy of Sciences under Grant No XDB07000000
文摘La（O,F）BiSe2 is a layered superconductor and has the same crystal structure with La（O,F）BiS2. We investigate the electronic structure of La（O,F）BiSe2 using the angle-resolved photoemission spectroscopy. Two electron-like Fermi surfaces around X（π, 0） are observed, corresponding to the electron doping of 0.23 per Bi site. We clearly resolve anisotropic band splitting along both Г-X and M-X due to the cooperative effects of large spin-orbit coupling and interlayer coupling. Moreover, we observe an almost non-dispersive electronic state around -0.2 eV between the electron-like bands. This state vanishes after in-situ K evaporation, indicating that it could be the localized surface state caused by defects on the cleaved surface.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11404002,11404003,and 11074001)the Scientific Research Foundation for the Returned Overseas Chinese Scholarsthe"211 Project"of Anhui University,China(Grant No.J01001319-J10113190007)
文摘We measure the current–voltage（I–V） characteristics for the single crystal of Tl0.4K0.41Fe1.71Se2 with the superconducting transition temperature（TC） around 30.5 K, under a 10 T magnetic field applied perpendicular and parallel to the ab plane. We find that the shapes of the I–V isotherms are very different from the description by the vortex-glass（VG） model.Combining theoretical calculations and analysis of the ρH⊥ab–T and ρH ab–T data, we give an explicit discussion over the suitability of the VG model for the A0.8Fe2Se2 superconductors, and point out the possibility of the material acting as a convenient platform for re-examination and further study of the complex vortex behaviors in the layered superconductors.
基金the National Natural Science Foundation of China(Grant No.19934003)the Research Fund for the Doctoral Program of Higher Education
文摘The influence of Gd doping at La-site on the electrical transport properties and the colossal magnetoresistance of La0.7-xGdxSr0.3MnO3 (x = 0.00, 0.10, 0.15, 0.20, 0.30, 0.40, 0.50, 0.60, and 0.70) is studied. The experimental results indicate that the transport properties exhibit abnormal behavior under high doping condition. For x = 0.50, we find that a transition from metal to insulator occurs after the occurrence of insulator-metal transition near Tc, which seldom occurs in ABO3 structure. For samples x = 0.60 and 0.70, it exhibits insulator behavior far above Tc. These abnormal behaviors are attributed to different magnetic background, i.e. the system undergoes a transition from long range ferromagnetic order to the cluster-spin glass state and further to antiferromagnetic order.
