High sensitivity SQUID susceptibility measurements

ORAL

Abstract

Scanning superconducting quantum interference device (SQUID) sensors have high sensitivity to magnetic flux ($ 10^{-6}\Phi_{0}/\sqrt{Hz} $) and magnetic moment ($\sim$ 100 electron spins) under reasonable scanning conditions. In addition, a single turn field coil co-centered with the SQUID sensing loop provides excitation for simultaneous measurement of low field susceptibility, with sensitivity of $\chi \sim 10^{-6}$ at a spatial resolution of a few microns. I will present our recent measurements on several systems which exhibit weak susceptometry signals: thin film paramagnetic LaNiO3 that are (hopefully) the precursors to engineered superconducting films; individual magnetotactic bacteria, which are used as MRI contrast agents; and twinned high critical temperature cuprate and pnictide superconducting samples that may experience variations in the superfluid density at the twin boundary.

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Authors

  • B. Kalisky

    • Stanford Unversity
    • Stanford

  • J.R. Kirtley

    • Stanford

  • L.C. Qian

    • Stanford

  • B.L. Dwyer

    • Stanford

  • K.A. Moler

    • Stanford

  • J. Ngai

    • Yale

  • Y. Segal

    • Yale

  • J. Reiner

    • Yale

  • F. Walker

    • Yale

  • C. Ahn

    • Yale

  • A.M. Hamilton

    • Stanford

  • B. Rutt

    • Stanford

  • A.C. Matin

    • Stanford

  • O.M. Auslaender

    • Technion

  • D.A. Bonn

    • UBC

  • R. Liang

    • UBC

  • W.N. Hardy

    • UBC

  • J.G. Analytis

    • Stanford

  • J.-H. Chu

    • Stanford

  • I.R. Fisher

    • Stanford