Grenzflächenmorphologie von GMR- und TMR-Schichtsystemen

The interface morphology of multilayer structures which are significant for the GMR and TMR effect was investigated by x-ray reflectivity and diffuse scattering. Besides the ex situ x-ray measurements at the Hamburg Synchrotron Laboratory experimantal work regarding the sample preparation and in situ characterization as well as the development of measurement methods and data modelling technique was accomplished. Co/Cu layers were grown by MBE on silicon and sapphire substrates and in situ characterization by Auger electron spectroscopy (AES) and low energy electron diffraction (LEED) was done. The morphology of a 50 Å thick fcc-Co(001) layer prepared at RT on a buffer system of Cu/Cr/Nb(001) upon a Al2O3(1-102) substrate was analysed before and after annealing at 175°C and 375°C employing anomalous x-ray scattering. The RMS roughness of the Co/Cu interface is about the same as for the upper Co interface (~5 Å) and a certain amount of vertical correlation of these interfaces is obvious from the diffuse x-ray scattering. The multilayer structure hardly changes after annealing at the aforementioned temperatures, since almost no change in the specular and diffuse x-ray scattering was observed. Several Co/Cu/Co(001) sandwich structures with interlayer thicknesses between 10 and 60 Å were prepared on a 2000 Å thick Cu(001) buffer on Si(001) at RT. The surface of the Cu(001) buffer has a RMS roughness of about 15 Å, a lateral correlation langth of a few hundred Å and a roughness exponent about 0.7. The surface structures of thereupon grown Co/Cu/Co(001) layers replicate this morphology to a rather high extent which is evident from a strong vertical correlation following from the x-ray diffuse scattering. X-ray reflectivity measurements were done to analyse the vertical layer structure of Co/Al2O3/NiFe TMR multilayers whose oxide barrier was prepared by UV light assisted oxidation. Several samples with oxidation times of 1, 2, 4, 8 and 16 minutes were measured. The structural properties of the oxide layer was partly determined only with low sensitivity, i. e. large uncertaincy and no correlation between the oxidation time and the morphology of the oxide layer whose thickness lies roughly between 10 and 20 Å could evidently be shown. The architecture of a Co/Al2O3/Co sandwich structure was systematically analyzed by x-ray reflectivity of several samples with an increasing number of layers. Due to a systematic mismatch which remained between data and modell calculations the results represent only rough estimates on the vertical layer structure and are in approximate agreement with the prepared layer thicknesses.

Grantor dc:publisher

Forschungszentrum Jülich, Zentralbibliothek

Year dc:date

2001

Author dc:creator

• Babik, Waldemar

Contributors dc:contributor

• Brückel, Thomas

• info:eu-repo/classification/ddc/530
• Kupfer
• Cobalt
• Mehrschichtsystem
• Grenzfläche
• Röntgenstreuung
• Aluminiumoxide
• Physik
• GMR
• TMR
• Reflektivität
• diffuse Streuung

Statement dc:rights

• info:eu-repo/semantics/openAccess

Language dc:language

ger

Identifier

https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-122014%22

OAI identifier oai:identifier

oai:publications.rwth-aachen.de:60293