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!