Fe/Mn/Fe wedged-shape sandwiches were prepared by molecular beam epitaxy under optimal conditions. The interlayer coupling measured by magneto-optic Kerr effect is very strong for thin Mn layers. The canted angle between the magnetization vectors of the two magnetic layers in remanence increases gradually from 0°t o about 180°and then gradually reduces to 90°for Mn thicknesses from 0.62 to 1.2 nm. For Mn layer thicknesses in the range between 1.2 and 2.45 nm, the interlayer coupling is always 90°coupling, but its strength oscillates with a short period of about 2 Mn monolayers. The above coupling phenomenon can be well described by the proximity magnetism model. ͓S0163-1829͑99͒50618-8͔Recently the mechanisms which couple ferromagnetic ͑FM͒ films across antiferromagnetic ͑AF͒ metallic interlayers have been of great interest. For AF interlayers one would expect a large contribution to the coupling coming from the direct nearest-neighbor exchange inside the interlayers and across the interfaces but since they are metals the indirect interaction due to the conduction electrons could be considered in addition. We consider here AF interlayers polarized in the plane of the film with sheets alternatively parallel and antiparallel to the magnetization of the FM films as observed by Walker and Hopster 1 on overlayers of Mn grown on Fe. In the ideal case one would expect oscillations of the coupling strength with a period of two monolayers ͑ML͒, with large amplitudes and sign changes.While this behavior has been studied in much detail for Cr interlayers and even a magnetic phase diagram for the Cr interlayer was deduced 2 which explains most of the experimental results, for Mn interlayer the situation is less clear. In the first work on Fe/Mn/Fe trilayers 3 Purcell et al. found interlayer coupling oscillations with a two ML period but there were no sign changes, indicating an appreciable background of AF coupling. On the contrary, Filipkowski et al. 4 found very strong near-90°coupling with no evidence for AF coupling in their CoFe/Mn/CoFe samples at room temperature. Also in contrast to the results in Fe/Mn/Fe trilayers, 3 the two ML period oscillations were absent in Co/Mn ͑Ref. 5͒ and Fe/Mn ͑Ref. 6͒ multilayers. Furthermore, the interlayer coupling in epitaxial Co/Mn multilayers 7 was attributed to the AF order of the Mn spacer. Unfortunately, the authors did not show the dependence of the interlayer coupling on the Mn layer thickness.In view of these contradictory results the aim of the present work was to prepare samples of the best possible quality which could provide reliable information on the coupling in this interesting system. Since this work and the evaluation of the experiments will be based on the assumption that we are here dealing with AF Mn as interlayer material we will use Slonczewki's proximity magnetism model 8 for the evaluation of the experiments. It will be briefly introduced in the next paragraph and compared with the usual method to evaluate such experiments.The proximity magnetism model 8 is a ph...
Stacked series arrays of intrinsic Josephson junctions were fabricated from Bi 2 Sr 2 CaCu 2 O 8+x thin films, deposited by high-oxygen-pressure dc sputtering. Stacks with areas between 2 × 2 µm 2 and 50 × 50 µm 2 , and thicknesses of 80-200 nm, were fabricated by photolithography and ion beam etching. We obtained RCSJ-like I -V curves with a critical current density of about 2 × 10 4 A cm −2 at 4.2 K. At high bias currents, we observed in some I -V curves many branches with gaps of about 10 mV corresponding to individual junctions. In addition, synchronized switching of more than 10 junctions was observed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.