Vibrating reed magnetometer studies of superconducting and magnetic materials

ABSTRACT

Applications of sensitive vibrating reed magnetometry to a variety of superconducting and magnetic materials are reviewed. The advantages of conducting vibrating reed studies of small single crystals, ceramics, thin films and multilayers with high anisotropy, composition gradients, strain and nonlinear magnetic response are documented. The equilibrium and dynamic properties of magnetic flux in superconductors, and coexistence of magnetic and superconducting states are emphasised. Vibrating reed experiments on Nb, NbSe₂, (Ba_0.6K_0.4)BiO₃, HoNi₂B₂C, {Nb(x)/Ni(y)}_Z multilayer films, and κ-(ET)₂Cu{N(CN)₂}Br have revealed subtle, exotic superconducting behaviours that remain unexplained. Future prospects for vibrating reed measurements of ferromagnetic thin films with patterned nanostructures are considered.

KEYWORDS:

• Measurements of magnetic anisotropy
• vibrating reed magnetometry
• magnetic measurements of superconductors
• magnetic measurements of ferromagnets
• magnetic measurements of thin-films and nanoscale materials

Acknowledgments

Research at the University of Kentucky was supported by U. S. National Science Foundation Grant No. DMR-1506979. LED would like to thank Prof. J. W. Brill for numerous conversations on vibrating reed techniques, including collaborative endeavours over many years, and W. Fuqua PE for technical assistance in conducting vibrating reed experiments. We thank Dr. Wentao Xu for providing unpublished, atomic-scale TEM images of Nb/Ni ML samples fabricated by Dr. Javier Villegas of the Universidad Complutense de Madrid (now at CNRS-Thales, France). We thank Dr. Amish G. Joshi (National Physical Laboratory, Delhi) for contributing unpublished VR data for Nb/Ni ML.

Disclosure statement

No potential conflict of interest was reported by the author(s).

ORCID

L. E. De Long http://orcid.org/0000-0003-2686-2736

A. P. Kaphle http://orcid.org/0000-0001-5195-913X

Additional information

Funding

This work was supported by U.S. National Science Foundation, Division of Materials Research Grant No DMR-1506979].