Tuning the onset of ferromagnetism in heterogeneous bimetallic nanoparticles by gas phase doping

Murtaza Bohra, Panagiotis Grammatikopoulos, Vidyadhar Singh, Junlei Zhao, Evropi Theodoratou, Stephan Steinhauer, Joseph Kioseoglou, Jean-François Bobo, Kai Nordlund, Flyura Djurabekova, Mukhles Sowwan

Research output: Contribution to journalArticleScientificpeer-review

Abstract

In the nanoregime, chemical species can reorganize in ways not predicted by their equilibrium bulk behavior. Here, we engineer Ni-Cr nanoalloys at the magnetic end of their compositional range (i.e., 0–15 at. % Cr), and we investigate the effect of Cr incorporation on their structural stability and resultant magnetic ordering. To ensure their stoichiometric compositions, the nanoalloys are grown by cluster beam deposition, a method that allows one-step, chemical-free fabrication of bimetallic nanoparticles. While full Cr segregation toward nanoparticle surfaces is thermodynamically expected for low Cr concentrations, metastability occurs as the Cr dopant level increases in the form of residual Cr in the core region, yielding desirable magnetic properties in a compensatory manner. Using nudged elastic band calculations, residual Cr in the core is explained based on modifications in the local environment of individual Cr atoms. The resultant competition between ferromagnetic and antiferromagnetic ordering gives rise to a wide assortment of interesting phenomena, such as a cluster-glass ground state at very low temperatures and an increase in Curie temperature values. We emphasize the importance of obtaining the commonly elusive magnetic nanophase diagram for M-Cr (M=Fe, Co, and Ni) nanoalloys, and we propose an efficient single-parameter method of tuning the Curie temperature for various technological applications.
Original languageEnglish
Article number066001
JournalPhysical Review Materials
Volume1
Issue number6
Number of pages12
ISSN2475-9953
DOIs
Publication statusPublished - 9 Nov 2017
MoE publication typeA1 Journal article-refereed

Fields of Science

  • 114 Physical sciences

Cite this

Bohra, M., Grammatikopoulos, P., Singh, V., Zhao, J., Theodoratou, E., Steinhauer, S., ... Sowwan, M. (2017). Tuning the onset of ferromagnetism in heterogeneous bimetallic nanoparticles by gas phase doping. Physical Review Materials, 1(6), [066001]. https://doi.org/10.1103/PhysRevMaterials.1.066001
Bohra, Murtaza ; Grammatikopoulos, Panagiotis ; Singh, Vidyadhar ; Zhao, Junlei ; Theodoratou, Evropi ; Steinhauer, Stephan ; Kioseoglou, Joseph ; Bobo, Jean-François ; Nordlund, Kai ; Djurabekova, Flyura ; Sowwan, Mukhles. / Tuning the onset of ferromagnetism in heterogeneous bimetallic nanoparticles by gas phase doping. In: Physical Review Materials. 2017 ; Vol. 1, No. 6.
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abstract = "In the nanoregime, chemical species can reorganize in ways not predicted by their equilibrium bulk behavior. Here, we engineer Ni-Cr nanoalloys at the magnetic end of their compositional range (i.e., 0–15 at. {\%} Cr), and we investigate the effect of Cr incorporation on their structural stability and resultant magnetic ordering. To ensure their stoichiometric compositions, the nanoalloys are grown by cluster beam deposition, a method that allows one-step, chemical-free fabrication of bimetallic nanoparticles. While full Cr segregation toward nanoparticle surfaces is thermodynamically expected for low Cr concentrations, metastability occurs as the Cr dopant level increases in the form of residual Cr in the core region, yielding desirable magnetic properties in a compensatory manner. Using nudged elastic band calculations, residual Cr in the core is explained based on modifications in the local environment of individual Cr atoms. The resultant competition between ferromagnetic and antiferromagnetic ordering gives rise to a wide assortment of interesting phenomena, such as a cluster-glass ground state at very low temperatures and an increase in Curie temperature values. We emphasize the importance of obtaining the commonly elusive magnetic nanophase diagram for M-Cr (M=Fe, Co, and Ni) nanoalloys, and we propose an efficient single-parameter method of tuning the Curie temperature for various technological applications.",
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author = "Murtaza Bohra and Panagiotis Grammatikopoulos and Vidyadhar Singh and Junlei Zhao and Evropi Theodoratou and Stephan Steinhauer and Joseph Kioseoglou and Jean-Fran{\cc}ois Bobo and Kai Nordlund and Flyura Djurabekova and Mukhles Sowwan",
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Bohra, M, Grammatikopoulos, P, Singh, V, Zhao, J, Theodoratou, E, Steinhauer, S, Kioseoglou, J, Bobo, J-F, Nordlund, K, Djurabekova, F & Sowwan, M 2017, 'Tuning the onset of ferromagnetism in heterogeneous bimetallic nanoparticles by gas phase doping', Physical Review Materials, vol. 1, no. 6, 066001. https://doi.org/10.1103/PhysRevMaterials.1.066001

Tuning the onset of ferromagnetism in heterogeneous bimetallic nanoparticles by gas phase doping. / Bohra, Murtaza; Grammatikopoulos, Panagiotis; Singh, Vidyadhar; Zhao, Junlei; Theodoratou, Evropi; Steinhauer, Stephan; Kioseoglou, Joseph; Bobo, Jean-François; Nordlund, Kai ; Djurabekova, Flyura ; Sowwan, Mukhles.

In: Physical Review Materials, Vol. 1, No. 6, 066001, 09.11.2017.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Tuning the onset of ferromagnetism in heterogeneous bimetallic nanoparticles by gas phase doping

AU - Bohra, Murtaza

AU - Grammatikopoulos, Panagiotis

AU - Singh, Vidyadhar

AU - Zhao, Junlei

AU - Theodoratou, Evropi

AU - Steinhauer, Stephan

AU - Kioseoglou, Joseph

AU - Bobo, Jean-François

AU - Nordlund, Kai

AU - Djurabekova, Flyura

AU - Sowwan, Mukhles

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Y1 - 2017/11/9

N2 - In the nanoregime, chemical species can reorganize in ways not predicted by their equilibrium bulk behavior. Here, we engineer Ni-Cr nanoalloys at the magnetic end of their compositional range (i.e., 0–15 at. % Cr), and we investigate the effect of Cr incorporation on their structural stability and resultant magnetic ordering. To ensure their stoichiometric compositions, the nanoalloys are grown by cluster beam deposition, a method that allows one-step, chemical-free fabrication of bimetallic nanoparticles. While full Cr segregation toward nanoparticle surfaces is thermodynamically expected for low Cr concentrations, metastability occurs as the Cr dopant level increases in the form of residual Cr in the core region, yielding desirable magnetic properties in a compensatory manner. Using nudged elastic band calculations, residual Cr in the core is explained based on modifications in the local environment of individual Cr atoms. The resultant competition between ferromagnetic and antiferromagnetic ordering gives rise to a wide assortment of interesting phenomena, such as a cluster-glass ground state at very low temperatures and an increase in Curie temperature values. We emphasize the importance of obtaining the commonly elusive magnetic nanophase diagram for M-Cr (M=Fe, Co, and Ni) nanoalloys, and we propose an efficient single-parameter method of tuning the Curie temperature for various technological applications.

AB - In the nanoregime, chemical species can reorganize in ways not predicted by their equilibrium bulk behavior. Here, we engineer Ni-Cr nanoalloys at the magnetic end of their compositional range (i.e., 0–15 at. % Cr), and we investigate the effect of Cr incorporation on their structural stability and resultant magnetic ordering. To ensure their stoichiometric compositions, the nanoalloys are grown by cluster beam deposition, a method that allows one-step, chemical-free fabrication of bimetallic nanoparticles. While full Cr segregation toward nanoparticle surfaces is thermodynamically expected for low Cr concentrations, metastability occurs as the Cr dopant level increases in the form of residual Cr in the core region, yielding desirable magnetic properties in a compensatory manner. Using nudged elastic band calculations, residual Cr in the core is explained based on modifications in the local environment of individual Cr atoms. The resultant competition between ferromagnetic and antiferromagnetic ordering gives rise to a wide assortment of interesting phenomena, such as a cluster-glass ground state at very low temperatures and an increase in Curie temperature values. We emphasize the importance of obtaining the commonly elusive magnetic nanophase diagram for M-Cr (M=Fe, Co, and Ni) nanoalloys, and we propose an efficient single-parameter method of tuning the Curie temperature for various technological applications.

KW - 114 Physical sciences

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DO - 10.1103/PhysRevMaterials.1.066001

M3 - Article

VL - 1

JO - Physical Review Materials

JF - Physical Review Materials

SN - 2475-9953

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ER -