Atomic Disorder Study in Ni alloys close to the Ferromagnetic Quantum Critical Point
ORAL
Abstract
This structural study, revealing the quality of selected Ni-alloys, Ni-V and Ni-Cr, aims to clarify the origin of magnetic clusters associated with the ferromagnetic-paramagnetic quantum phase transition driven by chemical substitution. Evidence for evolving magnetic clusters close to this disordered quantum critical point at a critical concentration xc=0.12 comes from muSR data [1] and recent neutron scattering data [2].
We present here a wide-angle neutron diffraction data and pair distribution function (PDF) analysis of both ferromagnetic Ni-alloys to check for the actual atomic distributions in polycrystalline samples prepared under different growth and annealing protocols.
Our PDF study uncovers that the atoms in Ni-V [3] and Ni-Cr are most likely randomly distributed on the lattice sites of the face-centered cubic (fcc) crystal structure for x<0.15. That confirms the ideal condition for a random distribution of “magnetic” clusters.
PDF data distinguish well simple random atom model from cluster and structure models. The results are sensitive to variation in the sample preparation and treatment. Only high temperature annealed samples yield the solid solution. Deviation from the protocol might lead to local inhomogeneities even to phase separation in Ni-Cr and Ni-V as demonstrated.
[1] R. Wang, A. Gebretsadik et al, “Quantum Griffiths phase inside the ferromagnetic phase in Ni1-xVx”, Phys Rev Lett 118, 267202 (2017)
[2] S. Bhattarai, H Adawi et al, “Evolution of short-range magnetic correlations in ferromagnetic Ni-V alloys”, Phys. Rev. B 107, 054409 (2023)
[3] A. Gebretsadik, et al, “Study of Atomic Disorder in Ni-V alloys”, arXiv:2302.1986, submitted to PRB
We present here a wide-angle neutron diffraction data and pair distribution function (PDF) analysis of both ferromagnetic Ni-alloys to check for the actual atomic distributions in polycrystalline samples prepared under different growth and annealing protocols.
Our PDF study uncovers that the atoms in Ni-V [3] and Ni-Cr are most likely randomly distributed on the lattice sites of the face-centered cubic (fcc) crystal structure for x<0.15. That confirms the ideal condition for a random distribution of “magnetic” clusters.
PDF data distinguish well simple random atom model from cluster and structure models. The results are sensitive to variation in the sample preparation and treatment. Only high temperature annealed samples yield the solid solution. Deviation from the protocol might lead to local inhomogeneities even to phase separation in Ni-Cr and Ni-V as demonstrated.
[1] R. Wang, A. Gebretsadik et al, “Quantum Griffiths phase inside the ferromagnetic phase in Ni1-xVx”, Phys Rev Lett 118, 267202 (2017)
[2] S. Bhattarai, H Adawi et al, “Evolution of short-range magnetic correlations in ferromagnetic Ni-V alloys”, Phys. Rev. B 107, 054409 (2023)
[3] A. Gebretsadik, et al, “Study of Atomic Disorder in Ni-V alloys”, arXiv:2302.1986, submitted to PRB
* The NPDF instrument at the Los Alamos Neutron Science Center, Los Alamos National Laboratory.The NOMAD instrument at the Spallation Neutron Source, a US Department of Energy Office of Science User Facility operated by Oak Ridge National Laboratory.HA acknowleges the supports Jazan University.
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Publication: [3] A. Gebretsadik, et al, "Study of Atomic Disorder in Ni-V alloys", arXiv:2302.1986, submitted to PRB
Presenters
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Hind Adawi
Jazan University
Authors
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Hind Adawi
Jazan University
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Arwa Alyami
Department of Physics, Kent State University
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Adane Gebretsadik
Kent state university
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Ruizhe Wang
Kent State University
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Jean-Guy Lussier
Kent state university
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Almut Schroeder
Kent State University
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Katharine Page
The University of Tennessee