The effect of addition of Ru to Fe on the electronic structure and magnetic properties

Kobayashi, Masaru; Ando, Noboru; Kai, Tadashi; Takano, Noriyuki; Shiiki, Kazuo

doi:10.1088/0953-8984/7/49/022

Cited by 12 publications

(17 citation statements)

References 28 publications

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“…According to recent band structure calculations [7] for Co 92 Ru 8 and Co 84 Ru 16 , this asymmetry decreases progressively with Ru content since the higher-lying Ru d-states give a contribution just around E F for both spin directions. This occurs because the Ru d-states are also exchange-split in Co at such small Ru concentrations (an exchange splitting of Ru d-states has been concluded also for Ni [31] and Fe [32] matrices from band structure calculations). Such an asymmetry change results in a reduction of the spin-dependent electron scattering and, thus, can lead to a diminution of the AMR as observed here in the Co 98.5 Ru 1.5 dilute alloy.…”

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confidence: 66%

Room temperature electronic transport properties of Co metal and Co(Ru) dilute alloys

Bakonyi¹,

Kádár²,

Tóth³

et al. 2002

Europhys. Lett.

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It turned out from room temperature electrical resistivity and magnetoresistance studies of electrodeposited Co metal and Co(Ru) dilute alloys that the incorporation of a small amount of Ru into Co significantly reduces the anisotropic magnetoresistance (AMR). The influence of Ru on the AMR of Co is explained by a drastic change of the asymmetry of d-band spin-up and spin-down electronic states at the Fermi level as revealed also by recent electronic band-structure calculations on Co-rich Co-Ru alloys.Introduction. -Extensive magnetoresistance (MR) studies have already been performed for magnetic/non-magnetic Co/Ru multilayers [1-4] and sandwiches [3,[5][6][7]. Although a clear giant magnetoresistance (GMR) effect has been observed in each case, its magnitude remained rather small (typically 0.1% at room temperature). This is in contrast to theoretical predictions made on the basis of the resistivity change caused by Ru impurities in a Co matrix [8]. It has been indicated in a recent study [5] that for Co/Ru multilayers and sandwiches, either sputtered or evaporated, a strong chemical intermixing occurs at the Co/Ru interface. It was argued that this intermixing, promoted by the complete mutual solubility of Co and Ru in the hexagonal close-packed (hcp) structure [9], leads to a strong reduction of both the GMR and the interlayer exchange coupling. In fact, the latter was found to be more than an order of magnitude smaller [5] than the theoretical prediction [10]. In view of the fact that a fairly large GMR is expected for the Co-Ru system, on the basis of the large spin asymmetry at the Fermi level [8], the observed GMR is, indeed, also very small.However, whereas the interlayer exchange coupling can certainly be very effectively reduced by interfacial intermixing [11][12][13], a weak antiferromagnetic coupling or the lack of coupling does not necessarily results in very small GMR [14]. For example, it has been demonstrated

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mentioning

confidence: 66%

Room temperature electronic transport properties of Co metal and Co(Ru) dilute alloys

Bakonyi¹,

Kádár²,

Tóth³

et al. 2002

Europhys. Lett.

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“…It is interesting to note that NPs A and C exhibit a soft ferromagnetic behavior at room temperature (coercive fields below 3 mT), while C is very close to a superparamagnetic material (coercive fields below 1 mT). Here, in contrast to Co, which normally induces a higher local magnetism, Ru plays a detrimental role for the local Fe magnetism . As a consequence, the “effective magnetic size” is reduced, leading to a reduced saturation magnetization and coercive field for C as compared to A and B .…”

Section: Resultsmentioning

confidence: 99%

“…Here, in contrast to Co, which normally induces a higher local magnetism, Ru plays a detrimental role for the local Fe magnetism. 35 As a consequence, the "effective magnetic size" is reduced, leading to a reduced saturation magnetization and coercive field for C as compared to A and B.…”

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confidence: 99%

Complex Nano-objects Displaying Both Magnetic and Catalytic Properties: A Proof of Concept for Magnetically Induced Heterogeneous Catalysis

et al. 2015

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Addition of Co2(Co)9 and Ru3(CO)12 on preformed monodisperse iron(0) nanoparticles (Fe(0) NPs) at 150 °C under H2 leads to monodisperse core-shell Fe@FeCo NPs and to a thin discontinuous Ru(0) layer supported on the initial Fe(0) NPs. The new complex NPs were studied by state-of-the-art transmission electron microscopy techniques as well as X-ray diffraction, Mössbauer spectroscopy, and magnetic measurements. These particles display large heating powers (SAR) when placed in an alternating magnetic field. The combination of magnetic and surface catalytic properties of these novel objects were used to demonstrate a new concept: the possibility of performing Fischer-Tropsch syntheses by heating the catalytic nanoparticles with an external alternating magnetic field.

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“…Fe-based alloys with 4d transition metals have been intensively investigated since the earliest studies on magnetic materials. Nevertheless, theoretical and experimental results on Fe-Ru systems are scarce [1][2][3][4][5][6][7][8][9][10][11]. Iron and ruthenium are miscible over the entire range of composition.…”

Section: Introductionmentioning

confidence: 99%

Theoretical study of the intrinsic magnetic properties of disordered Fe_1−xRu_xalloys: a mean-field approach

Paduani¹,

Branco²

2008

J. Phys.: Condens. Matter

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The magnetic properties of the Fe 1−x Ru x alloy system for 0 x 0.10 are studied by using a mean-field approximation based on the Bogoliubov inequality. Ferromagnetic Fe-Fe spin correlations and antiferromagnetic Fe-Ru and Ru-Ru exchanges have been considered for describing the temperature dependence of the Curie temperature and low temperature magnetization. A composition dependence has been imposed in the exchange couplings, as indicated by experiments. From a procedure of least-square fitting to the experimental results an estimation of the interaction parameters was obtained, which yielded the low temperature dependence of the magnetization and that of the ferromagnetic Curie temperature. Good agreement was obtained with available experimental results.

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The effect of addition of Ru to Fe on the electronic structure and magnetic properties

Cited by 12 publications

References 28 publications

Room temperature electronic transport properties of Co metal and Co(Ru) dilute alloys

Room temperature electronic transport properties of Co metal and Co(Ru) dilute alloys

Complex Nano-objects Displaying Both Magnetic and Catalytic Properties: A Proof of Concept for Magnetically Induced Heterogeneous Catalysis

Theoretical study of the intrinsic magnetic properties of disordered Fe_1−xRu_xalloys: a mean-field approach

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The effect of addition of Ru to Fe on the electronic structure and magnetic properties

Cited by 12 publications

References 28 publications

Room temperature electronic transport properties of Co metal and Co(Ru) dilute alloys

Room temperature electronic transport properties of Co metal and Co(Ru) dilute alloys

Complex Nano-objects Displaying Both Magnetic and Catalytic Properties: A Proof of Concept for Magnetically Induced Heterogeneous Catalysis

Theoretical study of the intrinsic magnetic properties of disordered Fe1−xRuxalloys: a mean-field approach

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Theoretical study of the intrinsic magnetic properties of disordered Fe_1−xRu_xalloys: a mean-field approach