In this study, we have explored the ways to fabricate and optimize high-quality ultrathin YBa2 Cu3 O7-δ(YBCO) films grown on single-crystal(001) SrTiO3 substrates. Nearly atomic-flat YBCO films are obtained by pulsed...In this study, we have explored the ways to fabricate and optimize high-quality ultrathin YBa2 Cu3 O7-δ(YBCO) films grown on single-crystal(001) SrTiO3 substrates. Nearly atomic-flat YBCO films are obtained by pulsed laser deposition.Our result shows that the termination of SrTiO3 has only a negligible effect on the properties of YBCO. In contrast, we found that capping a non-superconducting oxide layer can generally enhance the superconductivity of YBCO. PrBa2 Cu3 O7,La2 CuO4, LaMnO3, SrTiO3, and LaAlO3 have been examined as capping layers, and the minimum thickness of superconducting YBCO with capping is ~ 2 unit cells–3 unit cells. This result might be useful in constructing good-performance YBCO-based field effect devices.展开更多
Excellent epitaxial growth of supercon-ducting YBaCuOthin films have beenrealized on(100)SrTiOand(100)ZrOsubstrates by a planar rf or DC-magnetronsputtering apparatus with UHV system.Thequality of growth and the epita...Excellent epitaxial growth of supercon-ducting YBaCuOthin films have beenrealized on(100)SrTiOand(100)ZrOsubstrates by a planar rf or DC-magnetronsputtering apparatus with UHV system.Thequality of growth and the epitaxial orientationof the film strongly depended on substratetemperature,the substrate orientation and ox-ygen partial pressure.The films exhibitedsuperconducting onset at 92K and zero resist-ance at 90K with critical current density of展开更多
The patterning technologies and process order of high Tc(86K) super-conducting film bolometers have been studied. After the deposition, a conventional lithographic process was used to pattern the films with aqueous so...The patterning technologies and process order of high Tc(86K) super-conducting film bolometers have been studied. After the deposition, a conventional lithographic process was used to pattern the films with aqueous solution of HCl, and then the films were transferred into a tube furnace for annealing to form superconducting film. It eliminates the degradation of patterning process. The bolometric responsivity of approximately 34. 32 V/W is measured, and the detectivity is greater than 1. 62× 108cm · Hz1/2 · W-1, the noise equivalent powers NEP is 2. 1×10-9W.展开更多
Thin films of superconductors HoBa_2Cu_3O_(7-δ)(HBCO) were prepared by DC-sputtering technique. The epi-taxial growth was controlled by the ratio of the oxygen pressure and Ar pressure (O_2/Ar) , the subetrate temper...Thin films of superconductors HoBa_2Cu_3O_(7-δ)(HBCO) were prepared by DC-sputtering technique. The epi-taxial growth was controlled by the ratio of the oxygen pressure and Ar pressure (O_2/Ar) , the subetrate temperature T_s and the distance of the target to subetrate. Thin films deposited under the optimum conditions (Po_2/P_(Ar)= 1:2 ; T_s=730℃) show a critical temlierature clase to 87K and a transition width less than 1K. X-raydiffraction analysis shows that the films are highiy c-axis oriented. Auger electron spectroscopy depth profilingdemonstrates Ho diffusion into the Zr(Y)O_2 subetrate owing to the Ho subetitution for Y.展开更多
YBa2Cu3O7-x （YBCO） superconducting film was fabricated on {001} LaAlO3 （LAO） substrate by pulse laser deposition （PLD）, and its microstructure was examined by high resolution X-ray diffraction technology （HRXRD...YBa2Cu3O7-x （YBCO） superconducting film was fabricated on {001} LaAlO3 （LAO） substrate by pulse laser deposition （PLD）, and its microstructure was examined by high resolution X-ray diffraction technology （HRXRD）, such as pole figure, rocking curve, reciprocal space mapping. The results show that the YBCO crystalline alignment is almost {001}YBCO//{001}LAO, 100YBCO//100LAO besides 2% {001}YBCO//{001}LAO, 110YBCO//100LAO. The out-plane alignment of YBCO is some spreading （the breadth is 0.75°）. There are 90°±0.65°110 twin domains in the film, which is caused by the high local stress and stress difference between 100 and 010 during the tetragonal to orthorhombic phase transition.展开更多
One of the most promising near-term applications of high T_c superconductingfilms is in the area of passive microwave devices. The most remarkable feature ofthese microwave devices is that the high-frequency surface r...One of the most promising near-term applications of high T_c superconductingfilms is in the area of passive microwave devices. The most remarkable feature ofthese microwave devices is that the high-frequency surface resistance ofsuperconducting films is smaller than that of metal thin films. The size of themicrowave devices is dictated by wavelength and the thin films are generally requiredto be not smaller than a few square centimeters. Though pulsed laser deposition展开更多
Ⅰ. INTRODUCTION It has been proved that YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-x</sub> superconducting thin films can be epitaxially grown on SrTiO<sub>3</sub> by dc magn...Ⅰ. INTRODUCTION It has been proved that YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-x</sub> superconducting thin films can be epitaxially grown on SrTiO<sub>3</sub> by dc magnetron sputtering method with good lattice match along the axes However, for the epitaxial growth of YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-x</sub> superconducting thin film on Zr（Y）O<sub>2</sub>, its[100] direction is parallel to the[110] direction of Zr（Y）O<sub>2</sub> in stead of the lattice matching along the axes, which is due to the big mismatch between YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-x</sub>展开更多
Two-dimensional(2D)superconductors have intriguing physical properties and abundant potential applications.Recently,2D superconductingα-Mo2C and facecentered cubic Mo2C have been controllably prepared and they bring ...Two-dimensional(2D)superconductors have intriguing physical properties and abundant potential applications.Recently,2D superconductingα-Mo2C and facecentered cubic Mo2C have been controllably prepared and they bring new viewpoints to carbon-based superconductivity.Although molybdenum carbides(Mo-Cs)have multiple crystalline stacking orders,there are still few structures reported for the lack of higher energy supply during growth.In this study,we report a two-step vapor deposition method to grow superconducting η-Mo3C2 films with different thicknesses,with the assistance of controllable plasma power.The grownη-Mo3C2 films show polycrystalline characteristics,but they still present superior superconductivity.The 3.0-nm-thick film has the superconducting transition temperature of 5.38 K,and its electrical performances follow truly 2D superconducting transitions.This study will not only exhibit a robust superconductingη-Mo3C2 ultrathin film,but also provides a convenient growth way to realize more carbide-based heterostructures for future device applications.展开更多
Since the discovery of high temperature oxide superconductors in 1986, it is possible to adapt superconducting materials for technological applications at liquid nitrogen. One of the important applications is the fabr...Since the discovery of high temperature oxide superconductors in 1986, it is possible to adapt superconducting materials for technological applications at liquid nitrogen. One of the important applications is the fabrication of superconducting optical detector. This kind of device has good performances of wide response spectrum (from the visible to the millimeter),展开更多
Copper-doped Bi_(2)Se_(3)(Cu_(x)Bi_(2)Se_(3))is of considerable interest for tailoring its electronic properties and inducing exotic charge correlations while retaining the unique Dirac surface states.However,the copp...Copper-doped Bi_(2)Se_(3)(Cu_(x)Bi_(2)Se_(3))is of considerable interest for tailoring its electronic properties and inducing exotic charge correlations while retaining the unique Dirac surface states.However,the copper dopants in Cu_(x)Bi_(2)Se_(3) display complex electronic behaviors and may function as either electron donors or acceptors depending on their concentration and atomic sites within the Bi_(2)Se_(3) crystal lattice.Thus,a precise understanding and control of the doping concentration and sites is of both fundamental and practical significance.Herein,we report a solution-based one-pot synthesis of Cu_(x)Bi_(2)Se_(3) nanoplates with systematically tunable Cu doping concentrations and doping sites.Our studies reveal a gradual evolution from intercalative sites to substitutional sites with increasing Cu concentrations.The Cu atoms at intercalative sites function as electron donors while those at the substitutional sites function as electron acceptors,producing distinct effects on the electronic properties of the resulting materials.We further show that Cu_(0.18)Bi_(2)Se_(3) exhibits superconducting behavior,which is not present in Bi_(2)Se_(3),highlighting the essential role of Cu doping in tailoring exotic quantum properties.This study establishes an efficient methodology for precise synthesis of Cu_(x)Bi_(2)Se_(3) with tailored doping concentrations,doping sites,and electronic properties.展开更多
基金Project supported by the National Key Research and Development Program of the Ministry of Science and Technology of China(Grants Nos.2017YFA0303002and 2016YFA0300204)the Fundamental Research Funds for the Central Universities,China
文摘In this study, we have explored the ways to fabricate and optimize high-quality ultrathin YBa2 Cu3 O7-δ(YBCO) films grown on single-crystal(001) SrTiO3 substrates. Nearly atomic-flat YBCO films are obtained by pulsed laser deposition.Our result shows that the termination of SrTiO3 has only a negligible effect on the properties of YBCO. In contrast, we found that capping a non-superconducting oxide layer can generally enhance the superconductivity of YBCO. PrBa2 Cu3 O7,La2 CuO4, LaMnO3, SrTiO3, and LaAlO3 have been examined as capping layers, and the minimum thickness of superconducting YBCO with capping is ~ 2 unit cells–3 unit cells. This result might be useful in constructing good-performance YBCO-based field effect devices.
文摘Excellent epitaxial growth of supercon-ducting YBaCuOthin films have beenrealized on(100)SrTiOand(100)ZrOsubstrates by a planar rf or DC-magnetronsputtering apparatus with UHV system.Thequality of growth and the epitaxial orientationof the film strongly depended on substratetemperature,the substrate orientation and ox-ygen partial pressure.The films exhibitedsuperconducting onset at 92K and zero resist-ance at 90K with critical current density of
文摘The patterning technologies and process order of high Tc(86K) super-conducting film bolometers have been studied. After the deposition, a conventional lithographic process was used to pattern the films with aqueous solution of HCl, and then the films were transferred into a tube furnace for annealing to form superconducting film. It eliminates the degradation of patterning process. The bolometric responsivity of approximately 34. 32 V/W is measured, and the detectivity is greater than 1. 62× 108cm · Hz1/2 · W-1, the noise equivalent powers NEP is 2. 1×10-9W.
文摘Thin films of superconductors HoBa_2Cu_3O_(7-δ)(HBCO) were prepared by DC-sputtering technique. The epi-taxial growth was controlled by the ratio of the oxygen pressure and Ar pressure (O_2/Ar) , the subetrate temperature T_s and the distance of the target to subetrate. Thin films deposited under the optimum conditions (Po_2/P_(Ar)= 1:2 ; T_s=730℃) show a critical temlierature clase to 87K and a transition width less than 1K. X-raydiffraction analysis shows that the films are highiy c-axis oriented. Auger electron spectroscopy depth profilingdemonstrates Ho diffusion into the Zr(Y)O_2 subetrate owing to the Ho subetitution for Y.
基金Project (50972019) supported by the National Natural Science Foundation of ChinaProject (2011CBA00105) supported by the National Basic Research Program of China
文摘YBa2Cu3O7-x （YBCO） superconducting film was fabricated on {001} LaAlO3 （LAO） substrate by pulse laser deposition （PLD）, and its microstructure was examined by high resolution X-ray diffraction technology （HRXRD）, such as pole figure, rocking curve, reciprocal space mapping. The results show that the YBCO crystalline alignment is almost {001}YBCO//{001}LAO, 100YBCO//100LAO besides 2% {001}YBCO//{001}LAO, 110YBCO//100LAO. The out-plane alignment of YBCO is some spreading （the breadth is 0.75°）. There are 90°±0.65°110 twin domains in the film, which is caused by the high local stress and stress difference between 100 and 010 during the tetragonal to orthorhombic phase transition.
文摘One of the most promising near-term applications of high T_c superconductingfilms is in the area of passive microwave devices. The most remarkable feature ofthese microwave devices is that the high-frequency surface resistance ofsuperconducting films is smaller than that of metal thin films. The size of themicrowave devices is dictated by wavelength and the thin films are generally requiredto be not smaller than a few square centimeters. Though pulsed laser deposition
文摘Ⅰ. INTRODUCTION It has been proved that YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-x</sub> superconducting thin films can be epitaxially grown on SrTiO<sub>3</sub> by dc magnetron sputtering method with good lattice match along the axes However, for the epitaxial growth of YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-x</sub> superconducting thin film on Zr（Y）O<sub>2</sub>, its[100] direction is parallel to the[110] direction of Zr（Y）O<sub>2</sub> in stead of the lattice matching along the axes, which is due to the big mismatch between YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-x</sub>
基金the National Key R&D Program of China(2018YFA0305800)the Fundamental Research Funds for the Central Universities(020414380145 and 020414380153)+2 种基金the National Natural Science Foundation of China(11674154,11761131010,51972163,11904163,61974021 and 11525415)the Natural Science Foundation of Jiangsu Province(BK20190010)the Fok Ying-Tong Education Foundation of China(171038)。
文摘Two-dimensional(2D)superconductors have intriguing physical properties and abundant potential applications.Recently,2D superconductingα-Mo2C and facecentered cubic Mo2C have been controllably prepared and they bring new viewpoints to carbon-based superconductivity.Although molybdenum carbides(Mo-Cs)have multiple crystalline stacking orders,there are still few structures reported for the lack of higher energy supply during growth.In this study,we report a two-step vapor deposition method to grow superconducting η-Mo3C2 films with different thicknesses,with the assistance of controllable plasma power.The grownη-Mo3C2 films show polycrystalline characteristics,but they still present superior superconductivity.The 3.0-nm-thick film has the superconducting transition temperature of 5.38 K,and its electrical performances follow truly 2D superconducting transitions.This study will not only exhibit a robust superconductingη-Mo3C2 ultrathin film,but also provides a convenient growth way to realize more carbide-based heterostructures for future device applications.
基金Project supported by the High Technology Foundation of China
文摘Since the discovery of high temperature oxide superconductors in 1986, it is possible to adapt superconducting materials for technological applications at liquid nitrogen. One of the important applications is the fabrication of superconducting optical detector. This kind of device has good performances of wide response spectrum (from the visible to the millimeter),
基金the UCLA California NanoSystem Institute(CNSI)Noble Family Innovation Fund for material preparationpartial support from the National Science Foundation through grant number 2329192 for transport studies and analysis.
文摘Copper-doped Bi_(2)Se_(3)(Cu_(x)Bi_(2)Se_(3))is of considerable interest for tailoring its electronic properties and inducing exotic charge correlations while retaining the unique Dirac surface states.However,the copper dopants in Cu_(x)Bi_(2)Se_(3) display complex electronic behaviors and may function as either electron donors or acceptors depending on their concentration and atomic sites within the Bi_(2)Se_(3) crystal lattice.Thus,a precise understanding and control of the doping concentration and sites is of both fundamental and practical significance.Herein,we report a solution-based one-pot synthesis of Cu_(x)Bi_(2)Se_(3) nanoplates with systematically tunable Cu doping concentrations and doping sites.Our studies reveal a gradual evolution from intercalative sites to substitutional sites with increasing Cu concentrations.The Cu atoms at intercalative sites function as electron donors while those at the substitutional sites function as electron acceptors,producing distinct effects on the electronic properties of the resulting materials.We further show that Cu_(0.18)Bi_(2)Se_(3) exhibits superconducting behavior,which is not present in Bi_(2)Se_(3),highlighting the essential role of Cu doping in tailoring exotic quantum properties.This study establishes an efficient methodology for precise synthesis of Cu_(x)Bi_(2)Se_(3) with tailored doping concentrations,doping sites,and electronic properties.
