Presentation Title

Characterization of YBCO on LSAT and STO substrates using AFM and Resistance vs Temperature Measurements

Faculty Mentor

Shane Cybart

Start Date

18-11-2017 12:30 PM

End Date

18-11-2017 1:30 PM

Location

BSC-Ursa Minor 114

Session

Poster 2

Type of Presentation

Poster

Subject Area

engineering_computer_science

Abstract

Superconducting materials can be utilized to benefit and advance the medical field and other health facilities. YBa2Cu3O7 (YBCO) is a high-transition temperature superconductor that can be used to create Superconducting Quantum Interference Devices (or SQUIDs). SQUIDs have a wide range of uses; one of them is being able to detect small magnetic fields, which allows for improved magnetoencephalography (MEG) scanning. One of the important preliminary steps before creating these devices is the characterization of YBCO.

One characterization method we focus on is evaluating the resistance of YBCO through a Resistance vs Temperature Measurement setup. We evaluate the resistance of YBCO under a variety of substrates, such as LSAT and STO, to ensure the most ideal version of YBCO. Since the material can be grown in a variety of ways, we look for signs of lattice scattering and low residual resistivity to determine an ideal way of growth. The YBCO is connected to a circuit board using the Van der Pauw method, and is then placed into a probe which undergoes a liquid Nitrogen bath. The cold temperature allows the material to undergo superconductivity, which is around 90 Kelvin.

Another method of characterizing YBCO is mapping and determining the roughness of its surface through Atomic Force Microscopy (AFM). For YBCO to be utilized effectively, it needs to have a smooth surface down to the micrometer level. The smoother the YBCO is, the more viable the method of growth. AFM will allow us to visualize the average roughness of the material in a given area. Under the AFM microscope, a tip begins oscillating a cantilever along the surface of the material. This oscillation creates a visual image that outlines some major properties, such as mean roughness, maximum height, and depth of indentations.

Summary of research results to be presented

When testing YBCO grown on an STO substrate in Resistance vs Temperature Measurements, we found that the graph underwent superconductivity at its expected Temperature Coefficient of Resistance (Tc) and generated a smooth curve. The slope generated a relatively low amount of resistance, at 1.60 ohms. This resulted in the material having relatively low residual resistivity. YBCO grown under an LSAT substrate found a high amount of resistance at 65.0 ohms. This meant high residual resistivity due to impactful lattice scattering within the YBCO material.

Under Atomic Force Microscopy, we found that YBCO under STO substrate had an average roughness of 0.8-2.0 nm, compared to YBCO under LSAT substrate, with an average roughness of 6.0-9.0 nm. Overall, this led to the conclusion that YBCO grows better under STO, provided it is grown under the same conditions.

Additional experiments have compared the differences between unprocessed YBCO and YBCO that has gone under chemical etching. Further testing has also been done that suggests it is possible to visualize Josephson Junctions on processed, patterned thin-filmed YBCO under Atomic Force Microscopy.

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Nov 18th, 12:30 PM Nov 18th, 1:30 PM

Characterization of YBCO on LSAT and STO substrates using AFM and Resistance vs Temperature Measurements

BSC-Ursa Minor 114

Superconducting materials can be utilized to benefit and advance the medical field and other health facilities. YBa2Cu3O7 (YBCO) is a high-transition temperature superconductor that can be used to create Superconducting Quantum Interference Devices (or SQUIDs). SQUIDs have a wide range of uses; one of them is being able to detect small magnetic fields, which allows for improved magnetoencephalography (MEG) scanning. One of the important preliminary steps before creating these devices is the characterization of YBCO.

One characterization method we focus on is evaluating the resistance of YBCO through a Resistance vs Temperature Measurement setup. We evaluate the resistance of YBCO under a variety of substrates, such as LSAT and STO, to ensure the most ideal version of YBCO. Since the material can be grown in a variety of ways, we look for signs of lattice scattering and low residual resistivity to determine an ideal way of growth. The YBCO is connected to a circuit board using the Van der Pauw method, and is then placed into a probe which undergoes a liquid Nitrogen bath. The cold temperature allows the material to undergo superconductivity, which is around 90 Kelvin.

Another method of characterizing YBCO is mapping and determining the roughness of its surface through Atomic Force Microscopy (AFM). For YBCO to be utilized effectively, it needs to have a smooth surface down to the micrometer level. The smoother the YBCO is, the more viable the method of growth. AFM will allow us to visualize the average roughness of the material in a given area. Under the AFM microscope, a tip begins oscillating a cantilever along the surface of the material. This oscillation creates a visual image that outlines some major properties, such as mean roughness, maximum height, and depth of indentations.