Swift Iodine ion modification of the structural and magnetotransport properties of Fe/Cr systems

M. Kac (1) , J. Zukrowski (2) , M. Toulemonde (3) , R. Kruk (4) , V. Tokman (5) , A. Polit (1) , Y. Zabila (1) , A. Dobrowolska (1) , O. Synashenko (6) , M. Marszalek (1)

1 The Henryk Niewodniczanski Institute of Nuclear Physics PAN
2 Solid State Physics Department, Faculty of Physics and Applied Computer Science
3 CIMAP - UMR 6252 - Centre de recherche sur les Ions, les MAtériaux et la Photonique
4 Institute of Nanotechnology
5 IAP - Institute of Applied Physics of NASU
6 Sumy State University

Fe/Cr/Fe trilayers and (Fe/Cr)_20 multilayers prepared under ultrahigh vacuum conditions by thermal evaporation were irradiated with 200 MeV I^13+ ions in the fluence range between 1 x 10^11– 8 x 10^12 ions/cm2. The structural properties of the Fe/Cr/Fe trilayers and (Fe/Cr)_20 multilayers were measured by X ray reflectivity (XRR) and conversion electron Mössbauer Spectroscopy (CEMS). Magnetic exchange coupling between the Fe layers through the Cr spacer layer was observed by SQUID magnetization measurements. Magnetoresistance effect was measured using four probe method at room temperature. The XRR spectra showed an increase of the interface roughness versus increasing irradiation fluence in the multilayers, while in the trilayers smoothening of the interfaces in the sample irradiated with fluence equal to 4 x 10^11 I/cm2 and very slight change for other fluences were observed. Improving of the interface structure in the trilayers at this fluence was observed also by CEMS. Moreover the Mössbauer spectra also confirm roughening of the interfaces as a function of fluence for multilayers. Before irradiation an aniferromagnetic coupling fraction dominated in all samples. After irradiation the changes of magnetic coupling were different in both types of samples. The trilayers were less sensitive to the irradiation fluence than multilayers and increase of the antiferromagnetic fraction at small fluences was observed. In the multilayers continuous decrease of the antiferromagnetic fraction as a function of fluence was seen. Vanishing of the antiferromagnetic coupling, observed for the largest fluence, resulted in the decrease of magnetoresistance effect in the Fe/Cr multilayers.

Mots clés: Fe/Cr; multilayers; ion irradiation; interface roughness; magnetoresistance; antiferromagnetic coupling

Domaines: Science des matériaux [cond-mat.mtrl-sci]

M. Kac, J. Zukrowski, M. Toulemonde, R. Kruk, V. Tokman, et al.. Swift Iodine ion modification of the structural and magnetotransport properties of Fe/Cr systems. The Seventh International Symposium on Swift Heavy Ions in Matter, Jun 2008, Lyon, France. ⟨hal-00256380⟩