First-principle band calculation of ruthenium for various phases

Watanabe, Shoichi; Komine, Takashi; Kai, Tadashi; Shiiki, Kazuo

doi:10.1016/s0304-8853(00)00466-2

Cited by 23 publications

(29 citation statements)

References 10 publications

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“…2(a), the total energy of nonmagnetic (NM) bct Ru as a function of tetragonal distortion (c/a) is plotted for a fixed volume of the equilibrium bcc structure. Our result reproduces that given by Watanabe et al [12]: There is a global minimum at c/a = 1.41 corresponding to the fcc structure. There are two other extrema, a local maximum and minimum at c/a = 1 and c/a = 0.84, respectively.…”

Section: Resultssupporting

confidence: 92%

“…Equilibrium lattice constants of hexagonal-closed-packed (hcp), face-centered-cubic (fcc), and bcc Ru are summarized in Table I, which are in good agreement with experiments [11,24] and previous work [12]. The hcp structure is the most stable phase, as Ru crystallizes in hcp.…”

Section: Resultssupporting

confidence: 86%

“…In particular, c/a = 0.84 gives E = 35 meV/atom with a magnetic moment as high as 0.6μ B , which is larger than 0.40μ B in Ref. [12]. Interestingly, TABLE I.…”

Section: Resultsmentioning

confidence: 81%

“…In particular, the bct Ru film has been successfully fabricated on the Mo (110) substrate, whose lattice constants are a = 3.24Å and c/a = 0.83, as identified by x-ray electron diffraction [11]. Later, a theoretical calculation argued that magnetism can exist in bct Ru for c/a = 0.84 with a moment of 0.4μ B /atom [12]. In the cubic symmetry, such as bcc (c/a = 1), the d orbital splits into doublets (e g ) and triplets (t 2g ).…”

Section: Introductionmentioning

confidence: 99%

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Jahn-Teller driven perpendicular magnetocrystalline anisotropy in metastable ruthenium

et al. 2015

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A metastable phase of body-centered-tetragonal ruthenium (bct Ru) is identified to exhibit a large perpendicular magnetocrystalline anisotropy (PMCA), whose energy E MCA is as large as 150 μeV/atom, which is two orders of magnitude greater than those of 3d magnetic metals. Further investigation over the range of tetragonal distortion suggests that the appearance of magnetism in the bct Ru is governed by the Jahn-Teller spit e g orbitals. Moreover, from band analysis, MCA is mainly determined by an interplay between two e g states, d x 2 −y 2 and d z 2 states, as a result of level reversal associated with tetragonal distortion.

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Section: Resultssupporting

confidence: 92%

Section: Resultssupporting

confidence: 86%

“…In particular, c/a = 0.84 gives E = 35 meV/atom with a magnetic moment as high as 0.6μ B , which is larger than 0.40μ B in Ref. [12]. Interestingly, TABLE I.…”

Section: Resultsmentioning

confidence: 81%

Section: Introductionmentioning

confidence: 99%

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Jahn-Teller driven perpendicular magnetocrystalline anisotropy in metastable ruthenium

et al. 2015

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“…2a). Note that Ru d-band states up to 0.5eV above the Fermi energy can host at most 0.2μ B per spin direction and atom 32 . Therefore, further increase of the pump fluence and density of nonequilibrium electrons should result in a saturation of the spin current.…”

mentioning

confidence: 99%

Terahertz spin current pulses controlled by magnetic heterostructures

et al. 2013

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In spin-based electronics, information is encoded by the spin state of electron bunches 1,2,3,4 . Processing this information requires the controlled transport of spin angular momentum through a solid 5,6 , preferably at frequencies reaching the so far unexplored terahertz (THz) regime 7,8,9 . Here, we demonstrate, by experiment and theory, that the temporal shape of femtosecond spin-current bursts can be manipulated by using specifically designed magnetic heterostructures. A laser pulse is employed to drive spins 10,11,12 from a ferromagnetic Fe thin film into a nonmagnetic cap layer that has either low (Ru) or high (Au) electron mobility. The resulting transient spin current is detected by means of an ultrafast, contactless amperemeter 13 based on the inverse spin Hall effect 14,15 that converts the spin flow into a THz electromagnetic pulse. We find that the Ru cap layer yields a considerably longer spin-current pulse because electrons are injected in Ru d states that have a much smaller mobility than Au sp states 16 . Thus, spin current pulses and the resulting THz transients can be shaped by tailoring magnetic heterostructures, which opens the door for engineering high-speed spintronic devices as well as broadband THz emitters 7,8,9 , in particular covering the elusive range from 5 to 10THz.Contemporary electronics is based on the electron charge as information carrier whose presence or absence encodes the value of a bit. Much more efficient devices for low-power data storage and processing could be realized if the spin degree of freedom were used in addition 1,2,3,4 . The spintronics approach requires the generation and control of spin currents, that is, the transport of spin angular momentum through space 5,6 . Spintronic operations should be performed at a pace exceeding that of today's computers, which ultimately requires the generation of spin current pulses with terahertz (1 THz = 10 12 Hz) bandwidths 7,8 as well as the possibility to manipulate them in novel structures 17,18 . To date, femtosecond spin-current pulses have been successfully launched by optically exciting electrons in semiconductors 10 or ferromagnetic metals 11,12 . However, to enable ultrafast basic operations on these transients (such as buffering or delaying), their shape and propagation have to be controlled on subpicosecond time scales.Here, we employ magnetic heterostructures containing an optimally chosen nonmagnetic metallic layer whose electron mobility allows us either to trap or to transmit electrons and, thus, to engineer ultrafast spin pulses. The spin flow is probed in a contactless manner using the inverse spin Hall effect 14,15 (ISHE) that converts the spin current into a detectable THz electromagnetic pulse 13 . Our findings open up a route to device-oriented femtosecond spintronics as well as novel broadband emitters of THz radiation 7,8,9 .Our idea is illustrated in Fig. 1a, which shows a schematic of a ferromagnetic Fe film capped by a thin layer of Ru or Au. Absorption of a femtosecond laser pulse (photon energy 1...

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A Route for Phase Control in Metal Nanoparticles: A Potential Strategy to Create Advanced Materials

Kusada

Kitagawa

2015

Advanced Materials

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There is untapped potential for materials whose crystal structures are unobtainable in the bulk state. Several examples of such structures have been found in nanomaterials, and these materials exhibit unique properties that arise from their unique electronic states and surface structures. Here, recent developments in the syntheses of these nanomaterials and their unique properties, such as hydrogen-storage ability and catalytic activity, are summarized. Firstly, the syntheses and properties of novel solid-solution alloy nanoparticles in immiscible alloy systems such as Ag-Rh and Pd-Ru are introduced. Following this, the crystal structure control of nanoscale Ru is discussed. These unique alloy materials show enhanced properties and highlight the potential of phase control to be a new strategy for nanomaterial development.

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First-principle band calculation of ruthenium for various phases

Cited by 23 publications

References 10 publications

Jahn-Teller driven perpendicular magnetocrystalline anisotropy in metastable ruthenium

Jahn-Teller driven perpendicular magnetocrystalline anisotropy in metastable ruthenium

Terahertz spin current pulses controlled by magnetic heterostructures

A Route for Phase Control in Metal Nanoparticles: A Potential Strategy to Create Advanced Materials

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