The response of superconducting Nb films with a diluted triangular and square array of holes to a perpendicular magnetic field are investigated. Due to small edge-to-edge separation of the holes, the patterned films a...The response of superconducting Nb films with a diluted triangular and square array of holes to a perpendicular magnetic field are investigated. Due to small edge-to-edge separation of the holes, the patterned films are similar to multi-connected superconducting islands. Two regions in the magnetoresistance R（H） curves can be identified according to the field intervals of the resistance minima. Moreover, in between these two regions, variation of the minima spacing was observed. Our results provide strong evidence of the coexistence of interstitial vortices in the islands and fluxoids in the holes.展开更多
The response of superconducting Nb films with a diluted triangular and square array of holes to a perpendicular magnetic field are investigated.Due to small edge-to-edge separation of the holes,the patterned films are...The response of superconducting Nb films with a diluted triangular and square array of holes to a perpendicular magnetic field are investigated.Due to small edge-to-edge separation of the holes,the patterned films are similar to multi-connected superconducting islands.Two regions in the magnetoresistance R(H) curves can be identified according to the field intervals of the resistance minima.Moreover,in between these two regions,variation of the minima spacing was observed.Our results provide strong evidence of the coexistence of interstitial vortices in the islands and fluxoids in the holes.展开更多
A square hole array is fabricated over a micro-bridge of NbN thin film by electron beam lithography and reactive ion milling. Magneto-resistance is measured across the micro-bridge filled with a hole array near the su...A square hole array is fabricated over a micro-bridge of NbN thin film by electron beam lithography and reactive ion milling. Magneto-resistance is measured across the micro-bridge filled with a hole array near the superconducting transition temperature. It is found that magneto-resistance minima occur when the number of vortices is an integer multiple or a fractional multiple of the number of holes. The temperature and the current dependences of the matching effect are studied.展开更多
Fax-infraxed reflectivity spectra of bismuth germanium oxide （Bi12GeO20） single crystals are measured from room temperature down to 10 K. All the reflectivity spectra are fitted to a complex dielectric function ε...Fax-infraxed reflectivity spectra of bismuth germanium oxide （Bi12GeO20） single crystals are measured from room temperature down to 10 K. All the reflectivity spectra are fitted to a complex dielectric function ε（ω） in the factorised form. Phonon modes at low frequency are found to develop upon decreasing temperature and gain considerable spectrum weight below 150 K. The temperature-dependent static dielectric constants are obtained from the Lyddane-Sachs-Teller relation based on the obtained oscillator parameters. The dielectric constants are found to increase upon decreasing temperature, which is attributed to the charge transfer among the ions in the unit cell with the temperature varying.展开更多
Magnetoresistance in superconducting Nb films perforated with rectangular arrays of antidots （holes） is investigated at various temperatures and currents. Normally, the magnetoresistance increases with the increasin...Magnetoresistance in superconducting Nb films perforated with rectangular arrays of antidots （holes） is investigated at various temperatures and currents. Normally, the magnetoresistance increases with the increasing magnetic field. In this paper, we report a reverse behavior in a certain range of high fields after vortex reconfiguration transition, where the resistances at non-matching fields are smaller than those in the low field regime. This phenomenon is due to a strong caging effect, in which the interstitial vortices are trapped among the pinned multiquanta vortices. This effect is temperature and current dependent.展开更多
基金Project supported by the National Basic Research Program of China (Grant Nos. 2009CB929100 and 2011CBA00107)the National Natural Science Foundation of China (Grant Nos. 91121004,10974241,and 11104335)
文摘The response of superconducting Nb films with a diluted triangular and square array of holes to a perpendicular magnetic field are investigated. Due to small edge-to-edge separation of the holes, the patterned films are similar to multi-connected superconducting islands. Two regions in the magnetoresistance R（H） curves can be identified according to the field intervals of the resistance minima. Moreover, in between these two regions, variation of the minima spacing was observed. Our results provide strong evidence of the coexistence of interstitial vortices in the islands and fluxoids in the holes.
基金Project supported by the National Basic Research Program of China (Grant Nos. 2009CB929100 and 2011CBA00107)the National Natural Science Foundation of China (Grant Nos. 91121004,10974241,and 11104335)
文摘The response of superconducting Nb films with a diluted triangular and square array of holes to a perpendicular magnetic field are investigated.Due to small edge-to-edge separation of the holes,the patterned films are similar to multi-connected superconducting islands.Two regions in the magnetoresistance R(H) curves can be identified according to the field intervals of the resistance minima.Moreover,in between these two regions,variation of the minima spacing was observed.Our results provide strong evidence of the coexistence of interstitial vortices in the islands and fluxoids in the holes.
基金Project supported by the Comsats Institute of Information Technology, Islamabad, Pakistan,the National Natural Science Foundation of China (Grant No 10674168)the State Key Program for Basic Research of China (Grant No 2006CB601006)
文摘A square hole array is fabricated over a micro-bridge of NbN thin film by electron beam lithography and reactive ion milling. Magneto-resistance is measured across the micro-bridge filled with a hole array near the superconducting transition temperature. It is found that magneto-resistance minima occur when the number of vortices is an integer multiple or a fractional multiple of the number of holes. The temperature and the current dependences of the matching effect are studied.
基金Project supported by the National Natural Science Foundation of China (Grant No 10674168)Ministry of Science and Technology, China (Grant Nos 2006CB601006 and 2009CB930701)
文摘Fax-infraxed reflectivity spectra of bismuth germanium oxide （Bi12GeO20） single crystals are measured from room temperature down to 10 K. All the reflectivity spectra are fitted to a complex dielectric function ε（ω） in the factorised form. Phonon modes at low frequency are found to develop upon decreasing temperature and gain considerable spectrum weight below 150 K. The temperature-dependent static dielectric constants are obtained from the Lyddane-Sachs-Teller relation based on the obtained oscillator parameters. The dielectric constants are found to increase upon decreasing temperature, which is attributed to the charge transfer among the ions in the unit cell with the temperature varying.
基金Project supported by the National Basic Research Program of China (Grant Nos. 2009CB929100, 2011CBA00107, and 2012CB921302)the National Science Foundation of China (Grant Nos. 10974241 and 11104335)
文摘Magnetoresistance in superconducting Nb films perforated with rectangular arrays of antidots （holes） is investigated at various temperatures and currents. Normally, the magnetoresistance increases with the increasing magnetic field. In this paper, we report a reverse behavior in a certain range of high fields after vortex reconfiguration transition, where the resistances at non-matching fields are smaller than those in the low field regime. This phenomenon is due to a strong caging effect, in which the interstitial vortices are trapped among the pinned multiquanta vortices. This effect is temperature and current dependent.
