introduction squid ssm applications prospects anne arkenbout scanning squid microscopy scanning...
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Introduction
SQUID
SSM
Applications
Prospects
Anne Arkenbout
Scanning SQUID Microscopy
Scanning
SQUID
Microscopy
• New techniques to probe local properties
• Superconducting QUantum Interference
• Scanning SQUID Microscopy
J. R. Kirtley et al., Phys. Rev. Lett. 76 (1996), 1336-1339
Device
Introduction
SQUID
SSM
Applications
Prospects
Anne Arkenbout
Flux in a superconducting ring
Scanning
SQUID
Microscopy
• No resistance below critical temperature
• The magnetic flux is quantized
• Adjustment of supercurrent to maintain the quantisation
Introduction
SQUID
SSM
Applications
Prospects
Anne Arkenbout
Josephson junction
Scanning
SQUID
Microscopy
• Dc josephson effect
• Ac josephson effect
• J=J0sin (0+ 2e/h Vt )
V
superconductor Weak link
Introduction
SQUID
SSM
Applications
Prospects
Anne Arkenbout
Dc SQUID.
Scanning
SQUID
Microscopy
I/2-JI/2+J
I
Introduction
SQUID
SSM
Applications
Prospects
Anne Arkenbout
Scanning SQUID Microscope
Scanning
SQUID
Microscopy
• SQUID on a tip
• Local magnetic properties
• Refrigeration
Introduction
SQUID
SSM
Applications
Prospects
Anne Arkenbout
Spatial resolution
Scanning
SQUID
Microscopy
• SQUID – sample separation
• The smaller the loop the higher the spatial
resolution
• Maximal resolution ~ m
Introduction
SQUID
SSM
Applications
Prospects
Anne Arkenbout
Sensitivity
Scanning
SQUID
Microscopy
• Larger loop is higher sensitivity
• Up to 2x10-15 Tm2 ~ 1x10-10 T/(Hz)1/2
for a 7m2 SQUID
Introduction
SQUID
SSM
Applications
Prospects
Anne Arkenbout
SSM versus other techniques
Scanning
SQUID
Microscopy
• MFM
Spatial resolution: 10 – 100 nm
Sensitivity: pN ~ 10-6 T/(Hz)1/2
• Scanning Hall microscope
Spatial resolution: 0.8 m
Sensitivity: 3x10-8 T/(Hz)1/2
Introduction
SQUID
SSM
Applications
Prospects
Anne Arkenbout
Non destructive testing
Scanning
SQUID
Microscopy
• Current detection
• Corrosion
• Chip industry
J. Kirtley et al. Annu. Rev. Mater. Sci. (1999)29, 717
Introduction
SQUID
SSM
Applications
Prospects
Anne Arkenbout
High Tc superconductors
Scanning
SQUID
Microscopy
• The pairing symmetry of the Cooper pair
• Low Tc: spherical s-wave
• High Tc: d-wave
Introduction
SQUID
SSM
Applications
Prospects
Anne Arkenbout
Half integer flux quanta
Scanning
SQUID
Microscopy
• Detection set up
• Spontaneous flux formation
• Half integer flux quanta
J. R. Kirtley et al., Europhys. Lett., 36 (1996), 707-712
Introduction
SQUID
SSM
Applications
Prospects
Anne Arkenbout
Prospects
Scanning
SQUID
Microscopy
• Flux guide
T. Kondo et al., Physica C 392-396 (2003), 1401-1405
Introduction
SQUID
SSM
Applications
Prospects
Anne Arkenbout
Prospects
Scanning
SQUID
Microscopy
• Sample vibration technique
T. Kondo et al., Physica C 412-414 (2004),1501-1805
Introduction
SQUID
SSM
Applications
Prospects
Anne Arkenbout
Conclusion
Scanning
SQUID
Microscopy
• Poor spatial resolution
• Promissing recent developments
• Very good sensitivity
Introduction
SQUID
SSM
Applications
Prospects
Anne Arkenbout
Acknowledgement
Scanning
SQUID
Microscopy
I would like to thank prof. T. T. M. Palstra for supervising me during this project.
Introduction
SQUID
SSM
Applications
Prospects
Anne Arkenbout
Scanning
SQUID
Microscopy
Thank you for listening!
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