Scanning squid microscope for studying vortex matter in type-II superconductors

Common methods of local magnetic imaging display either a high spatial resolution and relatively poor field sensitivity (MFM, Lorentz microscopy), or a relatively high field sensitivity but limited spatial resolution (scanning SQUID microscopy). Since the magnetic field of a nanoparticle or nanostructure decays rapidly with distance from the structure, the achievable spatial resolution is ultimately limited by the probe-sample separation. This thesis presents a novel method for fabricating the smallest superconducting quantum interference device (SQUID) that resides on the apex of a very sharp tip. The nanoSQUID-on-tip displays a characteristic size down to 100 nm and a field sensitivity of 10^-3 Gauss/Hz^(1/2). A scanning SQUID microsope was constructed by gluing the nanoSQUID-on-tip to a quartz tuning-fork. This enabled the nanoSQUID to be scanned within nanometers of the sample surface, providing simultaneous images of sample topography and the magnetic field distribution. This microscope represents a significant improvement over the existing scanning SQUID techniques and is expected to be able to image the spin of a single electron. INDICE: Introduction.- Scientific Background.- Open Questions.- Goal.- Methods.- SQUID-on-tip Fabrication.- Tuning Fork Assembly.- Scanning SQUID Microscopy.- Fabrication of Samples.- Results.- SQUID-on-tip Characterization.- Imaging.- Discussion.- Appendices.

• ISBN: 978-3-642-29392-4
• Editorial: Springer
• Encuadernacion: Cartoné
• Fecha Publicación: 18/05/2012
• Nº Volúmenes: 1
• Idioma: Inglés