scholarly journals Al-driven peculiarities of local coordination and magnetic properties in single-phase Alx-CrFeCoNi high-entropy alloys

Nano Research ◽  
2021 ◽  
Author(s):  
Alevtina Smekhova ◽  
Alexei Kuzmin ◽  
Konrad Siemensmeyer ◽  
Chen Luo ◽  
Kai Chen ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Single Phase ◽  
Magnetic Circular Dichroism ◽  
Surface Region ◽  
Face Centered Cubic ◽  
X Rays ◽  
X Ray ◽  
High Entropy ◽  
X Ray Absorption ◽  
Absorption Edges

AbstractModern design of superior multi-functional alloys composed of several principal components requires in-depth studies of their local structure for developing desired macroscopic properties. Herein, peculiarities of atomic arrangements on the local scale and electronic states of constituent elements in the single-phase face-centered cubic (fcc)- and body-centered cubic (bcc)-structured high-entropy Alx-CrFeCoNi alloys (x = 0.3 and 3, respectively) are explored by element-specific X-ray absorption spectroscopy in hard and soft X-ray energy ranges. Simulations based on the reverse Monte Carlo approach allow to perform a simultaneous fit of extended X-ray absorption fine structure spectra recorded at K absorption edges of each 3d constituent and to reconstruct the local environment within the first coordination shells of absorbers with high precision. The revealed unimodal and bimodal distributions of all five elements are in agreement with structure-dependent magnetic properties of studied alloys probed by magnetometry. A degree of surface atoms oxidation uncovered by soft X-rays suggests different kinetics of oxide formation for each type of constituents and has to be taken into account. X-ray magnetic circular dichroism technique employed at L2.3 absorption edges of transition metals demonstrates reduced magnetic moments of 3d metal constituents in the sub-surface region of in situ cleaned fcc-structured Al0.3-CrFeCoNi compared to their bulk values. Extended to nanostructured versions of multicomponent alloys, such studies would bring new insights related to effects of high entropy mixing on low dimensions.

scholarly journals The Study of Magnetic Properties for Non-Magnetic Ions Doped BiFeO3

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4061
Author(s):  
Yongtao Li ◽  
Liqing Liu ◽  
Dehao Wang ◽  
Hongguang Zhang ◽  
Xuemin He ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Local Structure ◽  
Metal Ion ◽  
Single Phase ◽  
Sol Gel ◽  
X Ray ◽  
Co Doping ◽  
Magnetic Ions ◽  
X Ray Absorption ◽  
Fe Ions

BiFeO3 is considered as a single phase multiferroic. However, its magnetism is very weak. We study the magnetic properties of BiFeO3 by Cu and (Cu, Zn). Polycrystalline samples Bi(Fe0.95Cu0.05)O3 and BiFe0.95(Zn0.025Cu0.025)O3 are prepared by the sol-gel method. The magnetic properties of BiFe0.95(Zn0.025Cu0.025)O3 are greater than that of BiFeO3 and Bi(Fe0.95Cu0.05)O3. The analyses of X-ray absorption fine structure data show that the doped Cu atoms well occupy the sites of the Fe atoms. X-ray absorption near edge spectra data confirm that the valence state of Fe ions does not change. Cu and Zn metal ion co-doping has no impact on the local structure of the Fe and Bi atoms. The modification of magnetism by doping Zn can be understood by the view of the occupation site of non-magnetically active Zn2+.

scholarly journals Anisotropy of X-ray Absorption Cross Section in CeCoGe3 Single Crystal

Crystals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 544
Author(s):  
Andrei Rogalev ◽  
Fabrice Wilhelm ◽  
Elena Ovchinnikova ◽  
Aydar Enikeev ◽  
Roman Bakonin ◽  
...  
Keyword(s):  
Cross Section ◽  
Absorption Cross Section ◽  
Linear Dichroism ◽  
X Rays ◽  
Absorption Cross ◽  
X Ray ◽  
Measured Absorption ◽  
Linearly Polarized ◽  
X Ray Absorption ◽  
Absorption Edges

Absorption spectra of two orthogonal linearly polarized x-rays in a single CeCoGe3 crystal were measured at the ID12 beamline of the ESRF for the energies near the K-edges of Ge, Co and near the L23 edges of Ce. The X-ray natural linear dichroism (XNLD) was revealed in the vicinity of all the absorption edges, which indicates a splitting of electronic states in a crystalline field. Mathematical modelling in comparison with experimental data allowed the isotropic and anisotropic parts of atomic absorption cross section in CeCoGe3 to be determined near all measured absorption edges. The calculations also show that the “average” anisotropy of the cross section close to the Ge K-edge revealed in the experiment is less than the partial anisotropic contributions corresponding to Ge atoms in two different Wyckoff positions.

X-ray magnetic circular dichroism study of SmAl2 using the M4,5 x-ray absorption edges

2003 ◽  
Vol 93 (10) ◽  
pp. 8337-8339 ◽  
Author(s):  
S. S. Dhesi ◽  
P. Bencok ◽  
N. B. Brookes ◽  
G. van der Laan ◽  
R. M. Galéra
Keyword(s):  
Circular Dichroism ◽  
Magnetic Circular Dichroism ◽  
X Ray ◽  
X Ray Absorption ◽  
Circular Dichroïsm ◽  
Absorption Edges

scholarly journals STATE OFCoANDMnIN HALF-METALLIC FERROMAGNETCo2MnSiEXPLORED BY MAGNETIC CIRCULAR DICHROISM IN HARD X-RAY PHOTOELECTRON EMISSION AND SOFT X-RAY ABSORPTION SPECTROSCOPIES

SPIN ◽  
2014 ◽  
Vol 04 (04) ◽  
pp. 1440017 ◽  
Author(s):  
GERHARD H. FECHER ◽  
DANIEL EBKE ◽  
SIHAM OUARDI ◽  
STEFANO AGRESTINI ◽  
CHANG-YANG KUO ◽  
...  
Keyword(s):  
Magnetic Moment ◽  
Magnetic Circular Dichroism ◽  
Magnetic Moments ◽  
Magnetic Behavior ◽  
Photoelectron Spectra ◽  
X Rays ◽  
Half Metallic ◽  
X Ray ◽  
Magnetic Dichroism ◽  
X Ray Absorption

The half-metallic Heusler compound Co2MnSi is a very attractive material for spintronic devices because it exhibits very high tunnelling magnetoresistance ratios. This work reports on a spectroscopic investigation of thin Co2MnSi films as they are used as electrodes in magnetic tunnel junctions. The investigated films exhibit a remanent in-plane magnetization with a magnetic moment of about 5 μBwhen saturated, as expected. The low coercive field of only 4 mT indicates soft magnetic behavior. Magnetic dichroism in emission and absorption was measured at the Co and Mn  2p core levels. The photoelectron spectra were excited by circularly polarized hard X-rays with an energy of 6 keV and taken from the remanently magnetized film. The soft X-ray absorption spectra were taken in an induction field of 4 T. Both methods yielded large dichroism effects. An analysis reveals the localized character of the electrons and magnetic moments attributed to the Mn atoms, whereas the electrons related to the Co atoms contribute an itinerant part to the total magnetic moment.

Interrelation Between Structure and Magnetism of Ultra-Thin Mn Films Epitaxially Grown on (001) BCC Fe

1997 ◽  
Vol 475 ◽  
Author(s):  
S. Andrieu ◽  
Ph. Bauer ◽  
H. Fischer ◽  
M. Piecuch ◽  
M. Finazzi ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Electron Diffraction ◽  
Structural Transition ◽  
Magnetic Circular Dichroism ◽  
Magnetic Transition ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
X Ray ◽  
Structural And Magnetic Properties ◽  
X Ray Absorption

ABSTRACTIn this paper, the interrelation between structural and magnetic properties of ultra-thin Mn films epitaxially grown on (001) bcc Fe is studied. The Mn growth and in-plane structure were controlled by electron diffraction (RHEED). The structures of the Mn films were determined by using X-Ray absorption spectroscopy (SEXAFS). Finally, the magnetic properties were studied by using X-Ray magnetic circular dichroïsm (XMCD). All the experiments were performed under ultra-high vacuum. As shown by XMCD experiments, a magnetic transition is observed at 2 Mn monolayers. The analysis of RHEED and SEXAFS experimental results clearly demonstrates that a structural transition comes with this magnetic transition.

scholarly journals X-Ray Magnetic Circular Dichroism Spectroscopy and Microscopy

MRS Bulletin ◽  
1995 ◽  
Vol 20 (10) ◽  
pp. 41-44 ◽  
Author(s):  
N.V. Smith ◽  
H.A. Padmore
Keyword(s):  
Circular Dichroism ◽  
Magnetic Circular Dichroism ◽  
X Rays ◽  
Circularly Polarized ◽  
X Ray ◽  
Insertion Device ◽  
Magnetic Circular Dichroism Spectroscopy ◽  
Out Of Plane ◽  
X Ray Absorption ◽  
Circular Dichroïsm

The advent of electron accelerators dedicated to the production of high-intensity x-rays has revitalized experimental techniques based on x-ray absorption. A recent variant is to use circularly polarized x-rays generated either by use of out-of-plane radiation from a bending magnet or from a specially designed “insertion device.” This new field of x-ray magnetic circular dichroism (XMCD) shows considerable promise in spectroscopy and microscopy of magnetic materials. In this article, we describe the nature of XMCD, offer a few examples of recent progress, and review the prospects for future development using the newly constructed Advanced Light Source (ALS).

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