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@INPROCEEDINGS{Eich:907108,
author = {Eich, Andreas},
title = {{C}r{A}s at {L}ow {T}emperatures and {H}igh {P}ressures,
and the {D}evelopment of {C}lamp {C}ells for {N}eutron
{S}cattering {E}xperiments at the {MLZ}},
reportid = {FZJ-2022-01839},
year = {2022},
abstract = {Chromium Arsenide (CrAs) is the first reported Cr-based
superconductor, exhibiting superconductivity above ~0.3 GPa
with a maximum Tc ≈ 2.2 K at 1 GPa [1]. The
superconducting phase region with a dome-like shape lies in
the vicinity of a helically ordered antiferromagnetic state,
with a region of coexistence of magnetism and
superconductivity below ~0.7 GPa [2]. Short-range magnetic
fluctuations are assumed to play an essential role for the
pairing mechanism of the superconductivity, and CrAs is
considered to be a model system for the interplay of
superconductivity and helimagnetism [3].Up to now, most
studies on CrAs were focused on magnetic and transport
properties. The crystal structure of CrAs, however, has not
been conclusively investigated yet, especially in dependence
on the temperature. One aim of our investigation is thus to
give an overview of the complete structural behavior of CrAs
in dependence on temperature and on pressure. Our results
based on synchrotron X-ray single-crystal diffraction reveal
previously unknown features of CrAs related to the
first-order phase transition from the paramagnetic to the
antiferromagnetic state at TN ≈ 267 K: The isosymmetrical
transition can induce a change in the microstructure, and
one distinguished Cr–Cr distance exhibits anomalous
behavior [4].In addition, we investigated the magnetic
structure of CrAs at low temperature and high pressure by
means of neutron single-crystal diffraction. The results
show that the commonly accepted helical model is in fact not
suited to describe the structure, although an unambiguous
determination of the actually correct magnetic structure is
not possible on the basis of our data.For a direct
investigation of the crystal and magnetic structure of CrAs
in and near the superconducting phase region, neutron
scattering is the method of choice. To experimentally access
the low temperature/high pressure region, we have developed
two types of clamp cell suitable for use at the instruments
DNS, POLI and MIRA at the Heinz Maier-Leibnitz Zentrum (MLZ)
[5]. For each type, two variants were produced (CuBe and
NiCrAl “Russian Alloy”), working up to 1.1 GPa and 1.5
GPa, respectively. First tests were performed to determine
the load/pressure calibration curves (both with and without
neutron radiation), to estimate its neutron absorption and
background, and to measure magnetic reflections and the
thermal response. Future tests will help to establish the
cells at MLZ as a standard sample environment.},
organization = {(Digital) Institute Seminar JCNS-2
(PhD Rehearsal Talk), (Germany + online
event)},
subtyp = {Invited},
cin = {JCNS-2 / PGI-4 / JARA-FIT},
cid = {I:(DE-Juel1)JCNS-2-20110106 / I:(DE-Juel1)PGI-4-20110106 /
$I:(DE-82)080009_20140620$},
pnm = {632 - Materials – Quantum, Complex and Functional
Materials (POF4-632) / 6G4 - Jülich Centre for Neutron
Research (JCNS) (FZJ) (POF4-6G4)},
pid = {G:(DE-HGF)POF4-632 / G:(DE-HGF)POF4-6G4},
typ = {PUB:(DE-HGF)31},
url = {https://juser.fz-juelich.de/record/907108},
}