ELFT HÍRADÓ

[László Bottyán <bottyan.laszlo AT wigner.hun-ren.hu>]

English speakers please roll down.

Tisztelt Kollégák,

A Budapesti Neutronközpont soron következő (angol nyelvű) eseményére,

Wolfgang Kreutzpaintner (China Spallation Neutron Source):
"Development of In-situ Thin Film Growth for Polarized Neutron Reflectometry"

c. előadására szeretettel meghívjuk az érdeklődőket. Az előadás hossza
45 perc + diszkusszió

A jelenléti előadás a KFKI kampusz 26-os épületének tanácstermében

2024. április 4-én csütörtökön 14:00-kor kezdődik.

Az előadás kivonata és az előadó rövid szakmai életrajza alább olvasható.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Dear Colleagues,

Herewith you are cordially invited to participate the next in-person (EN 
language) BNC seminar entitled:

"Development of In-situ Thin Film Growth for Polarized Neutron Reflectometry"

to be given by

        Wolfgang Kreutzpaintner (China Spallation Neutron Source)

The 45 min seminar (+discussions) will take place in the seminar hall of 
MFA (1st floor, Bldg 26 of the KFKI campus) starting at

        2 p.m. on 4 April 2024 (Thursday).

Abstract:
Magnetic layers and heterostructures thereof are the fundamental building 
blocks of many commercial magneto-electronic devices, such as the read 
heads of hard disk drives or novel magnetic storage media like magnetic 
random-access memory (MRAM) or prototype racetrack memory structures.

The ultimate quality and performance of such devices crucially depends on 
the magnetic properties of the individual layers, their interfaces and the 
coupling between them. These properties are correlated with each other, 
and can be influenced by the specific processes during the thin film layer 
growth. For an optimization of the magnetic properties of thin films for 
scientific and technological applications, it is therefore essential to 
investigate the development of magnetism in layers and heterostructures in 
situ during growth and to correlate the evolving magnetism with the 
respectively evolving microstructures.

Such an in situ characterization of thin films by electron- and 
photon-based probes as well as by scanning probe techniques is common 
practice. However, growing thin films in situ directly in the neutron beam 
and investigating them at different deposition steps by (polarized) 
neutron reflectometry ((P)NR), is a technologically challenging task [1].

Here, the development work, carried out over one decade as a collaboration 
of TUM, University Augsburg and MPI Stuttgart, to realize and utilize a 
mobile sputtering facility [1,2,3] sample environment for the growth and 
in situ monitoring of magnetic multilayers by PNR at suitable neutron 
beamlines will be presented: as starting point, the early setup [2] and 
unpolarized & polarized proof of principle neutron reflectivity 
measurements on Ni/Cr and Fe thin films at the ToF reflectometer REFSANS 
at the FRM II neutron source will be shown. This will be followed by all 
the major development steps [2,3,4] and experimental milestones that 
ultimately allowed very fast in situ PNR measurements at the AMOR beamline 
at PSI to be performed. It is also a prime example of how an advanced 
sample environment for novel experiments needs the power of advanced 
neutron optics to fully unfold its capabilities.

The experiments [5,6] demonstrate that in situ PNR offers unique 
opportunities for answering a wide range of scientific questions at hand 
[1] and to potentially also advance the data analysis [7]. An overview 
over the latest developments and planned future modifications as well as 
the completion work carried out to allow the setup to be applied for even 
broader scientific research will conclude the talk.

As of 2023/2024, the setup has been transferred to and is permanently 
located at (and operated by) PSI, where it currently undergoes 
modifications to re-adapt it to the newly upgraded Amor beamline.

References:
[1] W. Kreuzpaintner, et al., Phys. Status Solidi B, 2100153 (2021). 
https://doi.org/10.1002/pssb.202100153
[2] A. Schmehl et al., Nucl. Inst. Meth. Phys. Res., A, 883, 170-183 
(2018). https://doi.org/10.1016/j.nima.2017.11.086
[3] J. Ye, et al., Nucl. Inst. Meth. Phys. Res., A, 163710 (2020). 
https://doi.org/10.1016/j.nima.2020.163710
[4] W. Kreuzpaintner, et al., Inst. Meth. Phys. Res., A 848, 144-152 
(2017). http://dx.doi.org/10.1016/j.nima.2016.12.017
[5] W. Kreuzpaintner et al., Phys. Rev. Applied, 7 (5), 054004 (2017). 
https://doi.org/10.1103/PhysRevApplied.7.054004
[6] S. Mayr, et al., Phys. Rev. B 101, 024404 (2020). 
https://doi.org/10.1103/PhysRevB.101.024404
[7] A. Book et al., Nucl. Inst. Meth. Phys. Res., A, 165970 (2022). 
https://doi.org/10.1016/j.nima.2021.165970

The speaker:
Wolfgang Kreuzpaintner was awarded his PhD in physics from the University 
of Hamburg, Germany in 2010, working in the group of Prof. Andreas 
Schreyer at the Geesthacht Neutron Facility (GENF). After the permanent 
shutdown of the Geesthacht research reactor, he joined the research group 
of Prof. Peter Böni at Technical University Munich as postdoctoral fellow 
in August 2010. There he habilitated in the field of Neutron 
Scattering in 2019. After a brief period as research fellow in Prof. Frank 
Klose’s group at the Guangdong Technion Israel Institute of Technology in 
Shantou, China, Wolfgang Kreuzpaintner joined the polarized neutron and 
sample environment group of the China Spallation Neutron Source/Institute 
of High Energy Physics in September 2019 as researcher at the equivalent 
level of a full professor. He is a member of the Chinese Academy of 
Sciences and serves as a Science and Technology Evaluation Expert of the 
Guangdong Province. His research interests are in novel spintronic, 
multiferroic and magnetic thin film materials with future applications in 
spintronic data storage and sensor technologies, as well as energy and 
battery materials. He is very active in developing neutron instrumentation 
and is strongly involved in the scientific discussions on a national and 
international level. He also regularly serves as organizer or committee 
member of international conferences, and as journal and grant reviewer.

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László Bottyán
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Budapest Neutron Centre
1121 Konkoly Thege Miklós út 29-33.
Budapest, Hungary
Phone: +361 392 2761
Fax:+361 395 9151
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