Abstract
The low-frequency resistance fluctuations of epitaxial thin films on different substrates have been studied as a function of temperature and applied magnetic field. A film with a high Curie temperature grown on a substrate with perfect lattice match shows a low overall noise amplitude, comparable to that of a conventional metal. In contrast to previous work, no increase of the resistance noise in the ferromagnetic regime of the film could be observed. The magnitude of the normalized resistance fluctuations decreases with decreasing temperature except for a sharp peak at this peak is completely suppressed by an applied magnetic field of about 2 T. In contrast, the noise level in a film with low Curie temperature grown on a substrate with large lattice mismatch (1.5%) is several orders of magnitude larger and shows a qualitatively different temperature dependence, with a huge noise increase below These results are discussed in terms of a strong coupling of electric resistance and magnetic ordering, as well as within a percolative picture of the ferromagnetic transition.
- Received 29 May 2000
DOI:https://doi.org/10.1103/PhysRevB.62.11619
©2000 American Physical Society