This title appears in the Scientific Report :
2018
Connecting MARIA with the MBE system: Polarized Neutron Reflectivity of thin Co films in UHV conditions using portable transport chamber
Connecting MARIA with the MBE system: Polarized Neutron Reflectivity of thin Co films in UHV conditions using portable transport chamber
MARIA is a dedicated instrument for neutron reflectometry of thin films. However, due to limited space a UHV system for thin film growth and in-situ measurements cannot be placed on-site. Hence, up to now thin films which are sensitive to ambient air have been fabricated in the MBE system located in...
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Personal Name(s): | Syed Mohd, Amir (Corresponding author) |
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Pütter, Sabine / Mattauch, Stefan / Brückel, Thomas | |
Contributing Institute: |
Streumethoden; JCNS-2 Streumethoden; PGI-4 JCNS-FRM-II; JCNS-FRM-II |
Imprint: |
2017
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Conference: | JCNS Workshop: Trends and Perspectives in Neutron Instrumentation: Probing Structure and Dynamics at Interfaces and Surfaces, Tutzing (Germany), 2017-10-10 - 2017-10-13 |
Document Type: |
Conference Presentation |
Research Program: |
Controlling Collective States FRM II / MLZ Jülich Centre for Neutron Research (JCNS) Quantum Condensed Matter: Magnetism, Superconductivity |
Subject (ZB): | |
Publikationsportal JuSER |
MARIA is a dedicated instrument for neutron reflectometry of thin films. However, due to limited space a UHV system for thin film growth and in-situ measurements cannot be placed on-site. Hence, up to now thin films which are sensitive to ambient air have been fabricated in the MBE system located in the thin film laboratory nearby and were covered by protecting cap layers in-situ. However these layers may change the physical properties of the sample, which is undesirable and prevents from further manipulation of the sample.Recently, we have solved this problem by developing a handy mini UHV transport chamber which is capable for both, sample transfer and polarized neutron reflectivity (PNR) measurements in UHV [1]. Our solution consists of a DN CF-40 cube with two opposing sapphire windows for the neutron beam, a combined non evaporable getter and ion pump for keeping the vacuum, a wobble stick, which is needed for in-situ sample transfer and also serves as sample holder for samples of up to 1 cm2 and a valve for sample exchange by mounting the chamber on the MBE system. The pressure in the transfer chamber is kept in the 10−10 mbar range during transport and PNR measurement.In this work, we present PNR of Co thin films with varying thickness deposited on Pt buffered MgO(001) substrates. The samples were prepared in the MBE and measured at MARIA under UHV condition using transport chamber at room temperature. During the measurement a field of 100 mT was applied parallel to the sample surface. We found that Co thin film is magnetically dead below 5 nm. However, magnetic moment in Co thin films evolves with increasing thickness and approaches to the bulk value (1.7 μB) above 3 nm. In addition, we also measured PNR of Co thin films after exposing with the ambient air. The fitting of the PNR data shows that surface of the Co film gets oxidised in air but remains free from contamination in UHV transport chamber.This project is part of the nanoscience foundry and fine analysis project (NFFA, www.nffa.eu) and has received funding from the EU’s H2020 research and innovation programme under grant agreement N. 654360.[1] A. Syed Mohd et al., Rev. Sci. Instrum., 87, 123909 (2016). |