Practical limits for detection of ferromagnetism using highly sensitive magnetometry techniques

• Type: Article in International Scientific Journal
• Date: 2011

Authors

pereira, l. m. c. (Author) Other; araujo, j. p. (Author) FCUP; van bael, m. j. (Author) Other; temst, k. (Author) Other; vantomme, a. (Author) Other

Journal

Title: Journal of Physics D: Applied Physics

Vol. 44

Final page: 215001

ISSN: 0022-3727

Publisher: Institute of Physics Publishing

Indexing

ISI Web of Knowledge - 45 Citations

Scopus - 48 Citations

Other information

Authenticus ID: P-002-R7E

DOI: 10.1088/0022-3727/44/21/215001

Abstract (EN): Over the last ten years, signatures of high temperature ferromagnetism have been found in thin films and nanoparticles of various materials which are non-ferromagnetic in bulk, from semiconductors to superconductors. These studies often involve state-of-the-art magnetometers working close to the limits of their sensitivity, where magnetic contaminations and measurement artefacts become non-negligible. Because such spurious effects may be involved, the reliability of magnetometry techniques for the detection of ferromagnetism in these new magnetic nanomaterials has been questioned. In this paper, we present a detailed study on magnetic contamination arising from sample processing and handling, describing how it may occur and how it can be avoided or otherwise removed. We demonstrate that, when proper procedures are followed, extrinsic magnetic signals can be reproducibly kept below 5 x 10(-7) emu (5 x 10(-10) A m(2)). We also give an overview of the expected levels of contamination when such optimum conditions cannot be guaranteed and analyse the characteristics of the resulting magnetic behaviour, discussing which features may or may not be used as criteria to distinguish it from intrinsic ferromagnetism. Although the measurements were performed using superconducting quantum interference device magnetometers, most of what we describe can also be applied when using alternating-gradient force and vibrating-sample magnetometers.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 10