Superconductor/Manganite Bilayer Thin Films in Cross Section

Superconductor/Manganite Bilayer Thin Films in Cross Section

Isaac Brown

2003-04

Introduction• Smooth Cross Sections

• Materials– Ceramic Superconductor: DyBa2Cu3O7

– Substrate: SrTiO3

– Manganite: La2/3Ba1/3MnO3

– Doped: LaMnO3

Applications•Electromagnets•Power

– Generation– Transportation

•Switching Devices

QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.

Method 1: Sandblaster

• Thinned substrate from the back with sandblaster

• Desired thickness after sandblasting: 50 µm

• Snapped thinned sample

Method 2: Polisher

• Polished fragment with diamond sandpaper

• Lubricated with– Water– Glycerol

Method 3: Microtome

• Embeded fragment in epoxy

• Cut off thin slices with glass knife

Measurements: AFM Height

• Measured height with an atomic force microscope

• Used 3 µm by 3 µm areas

• Took root mean squared

roughness readings on

full area and facets

• Desired value: 30 Å or less

Results: AFM Height

Results: AFM Height 2

Figure 5: Facet RMS

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22

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30

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34

Largest Smallest

Facets Ordered by Size

Facet RMS (Angstroms)

0

100

200

300

400

500

600

700

800

900

1000

Overall RMS (Angstroms)

FacetsOverall

Measurements: AFM Friction

• Took readings of relative friction so that different materials are distinctly visible

• Used to verify film quality and ability to be imaged

Results: Friction

Discussion: Facets

• Facet size does not affect facet RMS roughness

• Overall RMS roughness does not affect facet RMS roughness

• Facets are not arbitrary

Discussion: Methods

• Microtomy, using facets, was the smoothest usable method

• A film was imaged from only from one microtomy sample

• Epoxy and substrate should be minimized to protect film during microtomy

What Is Next?

• Scanning Tunneling Microscope– Spin-polarized current– Structure

• Supercondutor switching devices using the bilayer QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.

Acknowledgements

• Dr. Goldman

• Ms. Fruen

• Research class

• Everybody from the Goldman lab

Superconductor/Manganite Bilayer Thin Films in Cross Section

Isaac Brown

2003-04