Current Search: BSCCO (x)


Title

ANGULAR DEPENDENCE OF THE EMISSION FROM THE INTRINSIC JOSEPHSON JUNCTION IN PIESHAPED WEDGE TRIANGULAR BSCCO MESAS.

Creator

Morales, Manuel, Klemm, Richard, University of Central Florida

Abstract / Description

The purpose of this thesis is to determine the radiation patterns from an acute isosceles triangular superconducting mesa modeled by a pieshaped geometry. The terahertz band lies between the microwave and infrared regions of the electromagnetic spec trum. The terahertz radiation from atomicscale layered superconducting mesas is caused by the tunneling of electron pairs in the acJosephson effect. To determine the terahertz power radiated per unit solid angle of an acute isosceles...
Show moreThe purpose of this thesis is to determine the radiation patterns from an acute isosceles triangular superconducting mesa modeled by a pieshaped geometry. The terahertz band lies between the microwave and infrared regions of the electromagnetic spec trum. The terahertz radiation from atomicscale layered superconducting mesas is caused by the tunneling of electron pairs in the acJosephson effect. To determine the terahertz power radiated per unit solid angle of an acute isosceles triangular superconducting mesa, a model was employed in which the shape of the mesa is approximated as a pieshaped wedge. This model is shown to have an accuracy of about 1%. Using Love's Equivalency Principle, the current caused by the Josephson effect is then assumed to be on the edges of the mesa. Since in the mesas used for experiments the electric field is in the direction of the current, it is parallel to the boundary of the sample. Hence, we want the TM modes, and that requires the magnetic field to be transverse to the boundary. We thus require that the tangential component of the magnetic field parallel at the boundary vanishes. Love's equivalency principle provides the easiest and most straight forward way to satisfy this condition. The surface electric current density was modeled by comparing the magnetic vector potential re sulting from the modeled edge current with that given by a standard volume average integration technique. The surface current density that provided the best approximation to the bulk average was used and the radiation patterns were plotted using Mathematica software.
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Date Issued

2015

Identifier

CFH0004762, ucf:45345

Format

Document (PDF)

PURL

http://purl.flvc.org/ucf/fd/CFH0004762


Title

POWER DISTRIBUTION OF TERAHERTZ EMISSION FROM HEXAGONAL BSCCO MICROSTRIP ANTENNAS.

Creator

Davis, Andrew E, Klemm, Richard, University of Central Florida

Abstract / Description

We analyze the distribution of coherent terahertz radiation from a regular hexagonal microstrip antenna (MSA) made from the highTc superconductor Bi2Sr2CaCu2O8+x (BSCCO). We discuss the C6v symmetry of the solutions of the wave equation on a hexagonal domain and distinguish between the closedform and nonclosedform solutions. The closedform wavefunctions of the transverse magnetic (TM) electromagnetic cavity modes are presented and formulas for the radiated power arising from the uniform...
Show moreWe analyze the distribution of coherent terahertz radiation from a regular hexagonal microstrip antenna (MSA) made from the highTc superconductor Bi2Sr2CaCu2O8+x (BSCCO). We discuss the C6v symmetry of the solutions of the wave equation on a hexagonal domain and distinguish between the closedform and nonclosedform solutions. The closedform wavefunctions of the transverse magnetic (TM) electromagnetic cavity modes are presented and formulas for the radiated power arising from the uniform part of the AC Josephson current and from the resonant cavity modes are derived. The wavefunctions and angular distribution of radiation from both sources are plotted for sixteen of the lowestenergy modes. Finally, we comment on the relevance of these power distributions to hexagonal arrays of equilateral triangular MSAs and propose a strategy for studying the nonclosedform modes.
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Date Issued

2017

Identifier

CFH2000241, ucf:46016

Format

Document (PDF)

PURL

http://purl.flvc.org/ucf/fd/CFH2000241


Title

TERAHERTZ RADIATION FROM HIGHTEMPERATURE SUPERCONDUCTING BSCCO MESAS OF VARIOUS GEOMETRIES.

Creator

Cerkoney, Daniel, Klemm, Richard, University of Central Florida

Abstract / Description

The purpose of this thesis is to examine the radiation from hightemperature superconducting mesas of Bi2Sr2CaCu2O8+d (BSCCO). This is motivated by the need for coherent sources of continuous wave terahertz (THz) emission capable of radiating practically in the THz frequency band. As BSCCO has been shown to be tunable from 0.52.4 THz (i.e., through the entire socalled terahertz gap centered about 1 THz), and has a higher peak operating temperature near 1 THz than most alternative sources,...
Show moreThe purpose of this thesis is to examine the radiation from hightemperature superconducting mesas of Bi2Sr2CaCu2O8+d (BSCCO). This is motivated by the need for coherent sources of continuous wave terahertz (THz) emission capable of radiating practically in the THz frequency band. As BSCCO has been shown to be tunable from 0.52.4 THz (i.e., through the entire socalled terahertz gap centered about 1 THz), and has a higher peak operating temperature near 1 THz than most alternative sources, it is a good candidate for imaging and spectroscopy device applications. When a static DC voltage is applied to a BSCCO mesa, the stack of Josephson junctions intrinsic to this typeII layered superconductor synchronously radiate. Adjustment of the bath temperature and applied voltage allows for the high degree of tunability observed for such an emitter. To determine the angular dependence of radiation from BSCCO mesas, the dual source model from antenna theory is employed, and Love's equivalence principle is used to simplify this framework. The total emission power obtained in this manner for the pieshaped wedge is then fit to experimental results for a thin isosceles triangular mesa using the method of least squares, resulting in a standard deviation of 0.4657. Additionally, symmetry is shown to play a significant role in the emissions for the transverse magnetic (TM) cavity modes of the equilateral triangular mesa. When the full group symmetry is imposed, the density of allowed modes is heavily diminished, and the original first excited even mode becomes the C3v symmetric ground state. These results for the equilateral triangle suggest, along with earlier experiments on the regular pentagonal mesa, that symmetry breaking effects can be used for purposes of tuning the characteristic frequency and angular dependence of the power radiated from BSCCO mesas with a high degree of symmetry.
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Date Issued

2015

Identifier

CFH0004898, ucf:45429

Format

Document (PDF)

PURL

http://purl.flvc.org/ucf/fd/CFH0004898


Title

THE EFFECT OF IMPURITIES ON THE SUPERCONDUCTIVITY OF BSCCO2212.

Creator

Vastola, John, Klemm, Richard, University of Central Florida

Abstract / Description

BSCCO2212 is a hightemperature cuprate superconductor whose microscopic behavior is currently poorly understood. In particular, it is unclear whether its order parameter is consistent with swave or dwave symmetry. It has been suggested that its order parameter might take one of several forms that are consistent with dwave behavior. We present some calculations using the manybody theory approach to superconductivity that suggest that such order parameters would lead to a suppression of...
Show moreBSCCO2212 is a hightemperature cuprate superconductor whose microscopic behavior is currently poorly understood. In particular, it is unclear whether its order parameter is consistent with swave or dwave symmetry. It has been suggested that its order parameter might take one of several forms that are consistent with dwave behavior. We present some calculations using the manybody theory approach to superconductivity that suggest that such order parameters would lead to a suppression of the critical temperature in the presence of impurities. Because some experiments have suggested the critical temperature of BSCCO2212 is relatively independent of the concentration of impurities, this lends support to the hypothesis that its order parameter has swave symmetry.
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Date Issued

2016

Identifier

CFH2000073, ucf:45541

Format

Document (PDF)

PURL

http://purl.flvc.org/ucf/fd/CFH2000073