Resonant 3d, 3pand 3sPhotoemission in Transition Metal Oxides Predicted at 2pThreshold

Tanaka, A.; Jo, Takeo

doi:10.1143/jpsj.63.2788

Cited by 356 publications

(320 citation statements)

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“…In Fig. 2 To extract more detailed information concerning the charge and spin states from the Co-L 2,3 and the Mn-L 2,3 XAS spectra, we have carried out simulations of the XAS spectra using the well-proven configuration-interaction cluster model [14,15,16]. We studied a trigonal prism CoO 6 (an octahedral MnO 6 ) cluster, including the full atomic multiplet theory and the local effects of the solid.…”

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confidence: 99%

Ising Magnetism and Ferroelectricity inCa3CoMnO6

Burnus

et al. 2009

Phys. Rev. Lett.

131

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The origin of both the Ising chain magnetism and ferroelectricity in Ca3CoMnO6 is studied by ab initio electronic structure calculations and x-ray absorption spectroscopy. We find that Ca3CoMnO6 has the alternate trigonal prismatic Co 2+ and octahedral Mn 4+ sites in the spin chain. Both the Co 2+ and Mn 4+ are in the high spin state. In addition, the Co 2+ has a huge orbital moment of 1.7 µB which is responsible for the significant Ising magnetism. The centrosymmetric crystal structure known so far is calculated to be unstable with respect to exchange striction in the experimentally observed ↑↑↓↓ antiferromagnetic structure for the Ising chain. The calculated inequivalence of the Co-Mn distances accounts for the ferroelectricity.PACS numbers: 78.70.Dm, 71.27.+a Among a variety of multiferroic materials discovered so far [1,2], ferroelectric Ising chain magnet Ca 3 CoMnO 6 is quite unique, because the ferroelectricity (FE) is driven by exchange striction in a collinear Ising spin chain consisting of the charge ordered transition-metal ions [3]. The spin chain has the alternate trigonal prismatic and octahedral sites [3,4]. Special ↑↑↓↓ antiferromagnetic (AF) structure is detected in Ca 3 CoMnO 6 below T N ≈13 K by neutron diffraction. However, the measured magnetic moment of 0.66 µ B /Co and 1.93 µ B /Mn is much smaller than the expected one of the normal high-spin (HS) Co 2+ (S=3/2) and Mn 4+ (S=3/2). This led Choi et al. to a conclusion that the Co 2+ is (surprisingly) in a low-spin (LS) state [3]. In contrast, the effective magnetic moment of µ eff =5.8-6.0 µ B per formula unit (f.u.), extracted from magnetic susceptibility measurements above T N [4,5], suggests that both Co 2+ and Mn 4+ are in a HS state. Thus there is an apparent controversy between those data, and the problem concerning the spin state of, in particular, Co 2+ ions seems to be still unsolved. Another important question is to understand the nature of the Ising magnetism and of the resulting exchange striction, which are apparently crucial for the appearance of FE in Ca 3 CoMnO 6 . To this end, we carried out ab initio electronic structure calculations and x-ray absorption spectroscopy (XAS). We address the important issues including the Co/Mn site preference, their charge/spin/orbital states, the origin of the Ising magnetism, and the exchange striction.Our ab initio calculations were performed by using the full-potential augmented plane waves plus local orbital method (Wien2k code) [6]. We took the experimental centrosymmetric structure data of the rhombohedral lattice (R-3c) which has in a hexagonal setting the lattice constant a=9.1314Å and c=10.5817Å [4,7]. The calculations were done for different magnetic structures (↑↓↑↓, ↑↑↓↓, ↑↓↓↓, and ↑↑↑↑ orderings in the Co-Mn-CoMn chains). To study the exchange striction effect, we investigated the effect of internal atomic relaxation allowing the inversion symmetry to be broken in the ↑↑↓↓ spin chain, as discussed below. The muffin-tin sphere radii are chosen to be 2.4, 2.1 and 1.4 Bohr for ...

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confidence: 99%

Ising Magnetism and Ferroelectricity inCa3CoMnO6

Burnus

et al. 2009

Phys. Rev. Lett.

131

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“…This resonant channel consists of a virtual X-ray absorption process followed by an autoionization (or "participator Auger") decay. To lowest order in the autoionization operator V the transition operator T then becomes [45,49,50] …”

Section: Theoretical Formulationmentioning

confidence: 99%

Real-space Green's function approach to angle-resolved resonant photoemission: Spin polarization and circular dichroism in itinerant magnets

Pieve

Krüger

2013

Phys. Rev. B

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A first principles approach, based on the real space multiple scattering Green's function method, is presented for spin-and angle-resolved resonant photoemission from magnetic surfaces. It is applied to the Fe(010) valence band photoemission excited with circularly polarized X-rays around the Fe L3 absorption edge. When the photon energy is swept through the Fe 2p − 3d resonance, the valence band spectra are strongly modified in terms of absolute and relative peak intensities, degree of spin-polarization and light polarization dependence. New peaks in the spin-polarized spectra are identified as spin-flip transitions induced by exchange decay of spin-mixed core-holes. By comparison with single atom and band structure data, it is shown that both intra-atomic and multiple scattering effects strongly influence the spectra. We show how the different features linked to states of different orbital symmetry in the d band are differently enhanced by the resonant effect. The appearance and origin of circular dichroism and spin polarization are analyzed for different geometries of light incidence and electron emission direction, providing guidelines for future experiments.PACS numbers: 78.20. Bh, 78.20.Ls, In the last decade, magnetic circular dichroism (MCD) and spin polarization studies in resonant inelastic X-ray scattering (RIXS) and resonant photoemission (RPES) have acquired great importance in the study of magnetic and correlated materials. Such spectroscopies probe respectively the radiative and non radiative autoionization decay of a core hole, and the signal can be strongly enhanced with respect to the non resonant mode. The element and orbital selectivity of core level resonant spectroscopies allows to access higher order multipoles which are left unexplored by MCD in X-ray absorption (XAS) [1][2][3][4][5][6], to distinguish and enhance specific electronic excitations and satellites [7,8], collective magnetic excitations [9], ultrafast and charge transfer dynamics [10][11][12] and to detect quadrupolar transitions towards localized empty states [13,14]. In particular, RPES has recently been applied to several correlated materials [15][16][17][18][19] and full two dimensional angular scans of resonantly emitted electrons in moderately correlated materials have also been carried out [20,21]. These works, together with earlier pioneering studies [22,23] on local magnetic properties in macroscopically non magnetic systems, demonstrate the importance of RPES and the need for an advancement in the theoretical description of this spectroscopy, which is the main aim of this work.RPES is in principle an autoionization channel of the * Electronic address: fabiana.dapieve@gmail.com more general process called resonant Auger decay. Depending on whether the core-excited electron participates or not in the Auger decay, the process is termed either participator or spectator channel. In the participator channel the one hole final state is degenerate with the one in direct valence band photoemission (PES, or ARPES if angle reso...

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“…To extract information on the magnetic ordered states, we analyzed the line shapes by using cluster model calculations with full atomic multiplets and configuration interactions, the so-called CI calculations [30]. The calculated MCD spectra for FeO 6 Figure 3 shows the calculated MCD spectra for the L 3 region, in comparison with the experimental ones, and the spin structures for x ¼ 0.00 and x ¼ 0.08 at H ab ¼ 6000 Oe and H c ¼ 6000 Oe.…”

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confidence: 99%

Magnetic Origin of Giant Magnetoelectricity in Doped Y-type HexaferriteBa0.5Sr1.5Zn2(
Noh
¹
,
Ko
²
,
Chun
³

et al. 2015
Phys. Rev. Lett.
30
0
5
0
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We investigated site-specific magnetic behaviors of multiferroic Ba 0.5 Sr 1.5 Zn 2 ðFe 1−x Al x Þ 12 O 22 using Fe L 2;3 -edge x-ray magnetic circular dichroism. The Al dopants mostly replace the Fe 3þ ions at octahedral (O h ) sites, which contribute unquenched angular momenta through off-centering displacements. This replacement greatly reduces the magnetic anisotropy energy to change the magnetic order from a helical to a heliconical type with enhanced magnetoelectric susceptibility (α ME ). The tetrahedral (T d ) Fe sites exhibit magnetic hysteresis distinguishable from that of the O h sites, especially at low magnetic fields. These results provide essential clues for the heliconical order with a giant α ME and multibit memory effects in the Al-doped Y-type hexaferrite. Multiferroic materials, in which magnetism and ferroelectricity coexist with a cross coupling, the so-called magnetoelectric (ME) effect, have been intensively studied experimentally and theoretically over the past decade due to their potential technological applications as nextgeneration multibit memory devices [1][2][3]. The ME effect was demonstrated in various multiferroic materials such as chromates, manganites, ferrites, etc. [1-6], and spiral, cycloidal, or noncollinear helical magnetic orders were known to be essential for a large ME effect [7][8][9][10][11]. Multiferroicity is well explained by an inverse Dzyaloshinskii-Moriya interaction [12,13] or a spin-current model [14]. However, most of the materials were recognized to face the difficulty of application barriers due to the low ME response, low ME temperature, and/or the requirement of a high magnetic field. Recently, hexaferrites with several different types have attracted much attention as candidates for possible multiferroic application materials with a giant ME susceptibility (α ME ) at a relatively high temperature [4,[15][16][17], and even nonvolatile multistate behaviors were demonstrated at room temperature [18]. Particularly in Y-type hexaferrites ðBa; SrÞ 2 Zn 2 Fe 12 O 22

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Resonant 3d, 3pand 3sPhotoemission in Transition Metal Oxides Predicted at 2pThreshold

Cited by 356 publications

References 26 publications

Ising Magnetism and Ferroelectricity inCa3CoMnO6

Ising Magnetism and Ferroelectricity inCa3CoMnO6

Real-space Green's function approach to angle-resolved resonant photoemission: Spin polarization and circular dichroism in itinerant magnets

Magnetic Origin of Giant Magnetoelectricity in Doped Y-type HexaferriteBa0.5Sr1.5Zn2(
Noh
¹
,
Ko
²
,
Chun
³

et al. 2015
Phys. Rev. Lett.
30
0
5
0
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Resonant 3d, 3pand 3sPhotoemission in Transition Metal Oxides Predicted at 2pThreshold

Cited by 356 publications

References 26 publications

Ising Magnetism and Ferroelectricity inCa3CoMnO6

Ising Magnetism and Ferroelectricity inCa3CoMnO6

Real-space Green's function approach to angle-resolved resonant photoemission: Spin polarization and circular dichroism in itinerant magnets

Magnetic Origin of Giant Magnetoelectricity in Doped Y-type HexaferriteBa0.5Sr1.5Zn2(Noh1, Ko2, Chun3 et al. 2015Phys. Rev. Lett.30050View full textAdd to dashboardCite

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Magnetic Origin of Giant Magnetoelectricity in Doped Y-type HexaferriteBa0.5Sr1.5Zn2(
Noh
¹
,
Ko
²
,
Chun
³

et al. 2015
Phys. Rev. Lett.
30
0
5
0
View full text Add to dashboard Cite