Temperature- and pressure-induced spin-state transitions in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mi>LaCoO</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:mrow></mml:math>

Vankó, György; Rueff, Jean‐Pascal; Mattila, Aino K.; Németh, Zoltán; Shukla, Abhay

doi:10.1103/physrevb.73.024424

Cited by 182 publications

(174 citation statements)

References 57 publications

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“…In a recent study on cobaltates, the IADs were found varying linearly with the spin. 40 These observations suggest that the IAD has the potential to extend the quantitative spin momentum determination to general cases.…”

Section: Determination Of the Spin Momentum From Xesmentioning

confidence: 94%

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Probing the 3d Spin Momentum with X-ray Emission Spectroscopy: The Case of Molecular-Spin Transitions

et al. 2006

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We report X-ray emission spectra of Fe III , Fe II , and Co II spin-crossover compounds in their high-spin and low-spin forms. It is shown that all X-ray emission features are sensitive to the spin state. Variations of the K and the KR emission line shapes, which are in agreement with theory, can be used as quantitative probes of the spin state; it is suggested that with appropriate reference experiments one can extract the spin momentum for a general case. Resonant X-ray emission spectra unveil details of the redistribution of electrons on the 3d levels associated with the spin-state change by revealing features at the X-ray absorption preedge not accessible through standard absorption measurements.

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Section: Determination Of the Spin Momentum From Xesmentioning

confidence: 94%

“…25,40 Let us note the HS and LS XE spectral functions as h(E) and l(E), respectively, which are normalized to unit area at integration. Using them, the IAD value for the complete spin transition can be given as IAD HL ) ∫|h(E) -l(E)| dE.…”

Section: Determination Of the Spin Momentum From Xesmentioning

confidence: 99%

Probing the 3d Spin Momentum with X-ray Emission Spectroscopy: The Case of Molecular-Spin Transitions

et al. 2006

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“…In insulators a small intensity of the Kβ' feature is taken as an indication of a low-spin state and this spectral signature has been widely used to identify transitions from high-to low-spin as a function of pressure [16], temperature [17] or composition [18]. For metallic systems it has been observed that the Kβ' feature is very broad [19].…”

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confidence: 99%

Evidence of Mott physics in iron pnictides from x-ray spectroscopy

et al. 2017

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X-ray emission and absorption spectroscopies are jointly used as fast probes to determine the evolution as a function of doping of the fluctuating local magnetic moments in K-and Cr-holedoped BaFe 2 As 2 . An increase in the local moment with hole-doping is found, supporting the theoretical scenario in which a Mott insulating state that would be realized for half-filled conduction bands has an influence throughout the phase diagram of these iron-pnictides.A scenario has recently been proposed in the field of Fe-based superconductors, where the low energy physics is described in terms of a coexistence of strongly and weakly correlated electrons [1]. Such a picture provides a framework to understand a wealth of experiments on quasiparticle mass enhancements (specific heat, low-frequency optical conductivity, angleresolved photoemission spectroscopy, quantum oscillations etc.) in electron-and hole-doped A direct method to probe the local magnetic moment in transition metal compounds is Kβ coreto-core (CTC) x-ray emission spectroscopy (XES) that is sensitive to the local 3d spin because of the intra-atomic 3p-3d exchange interaction [5,6] The unoccupied density of states around Fe can be probed by means of K edge x-ray absorption spectroscopy (XAS) providing information that is complementary to Kβ spectroscopy. We have recorded high-energy resolution fluorescence detected XAS on all K-and Cr-doped samples.All samples were plate-like single crystals grown by the self-flux technique as detailed elsewhere (111) monochromator crystals. The inelastically scattered photons were analyzed using a set of five spherically bent Ge(620) crystals that were arranged with the sample and detector (avalanche photodiode) in a vertical Rowland geometry (R = 1 m). The surface of the samples was aligned to 45º with respect to the incident beam direction, i.e. the angle between the electric field of the linearly polarized x-rays and the sample [001] direction. Non-resonant Fe Kβ XES measurements were recorded at incident energy 7200 eV. High-energy resolution fluorescence-detected x-ray absorption near edge structure (HERFD-XANES) spectra were obtained by setting the emission energy to the maximum of the Kβ 1,3 line while scanning the incoming energy through the absorption edge. The resulting spectrum is an approximation to the 1s photoabsorption cross section with sharper spectral features than in standard XAS [5,6]. The total experimental broadening, determined as full width at half maximum of the elastic profiles, was 1.3 eV. All the measurements were performed at room temperature. Both XES and HERFD-XANES spectra have been normalized in area using the ranges 7025-7080 eV and 7105-7190 eV respectively.Non-resonant Fe Kβ CTC XES spectra have been measured as a function of doping in Ba 1-x K x Fe 2 As 2 (0 ≤ x ≤ 1) and Ba(Fe 1-x Cr x ) 2 As 2 (0.026 ≤ x ≤ 0.47). Figure 1( [20] where J is the exchange integral between the electrons in the 3p and 3d shells. It becomes visible in the difference spectra of Figure 1 and is about 10-...

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“…It is well known that applying pressure stabilizes the LS state relative to the HS state owing to its small ionic ra- * dius. 13,14) The ion substitution, the thin-film synthesis, and the pulse-laser irradiation also bring about the spin-state change. [25][26][27][28][29] Magnetic field is a promising tool to control the spin states.…”

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Magnetic Field Effects in a Correlated Electron System with Spin-State Degree of Freedom — Implications for an Excitonic Insulator —

et al. 2016

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Magnetic field (H) effects on a correlated electron system with the spin-state degree of freedom are examined. The effective Hamiltonian derived from the two-orbital Hubbard model is analyzed by the mean-field approximation. Applying H to the low-spin (LS) phase induces the excitonic insulating phase, as well as the spin-state ordered phase where the LS and high-spin (HS) states are ordered alternately. In the case where H is applied to the HS phase, a reentrant transition for the HS phase appears. A rich variety of the phase diagrams are attributed to the spin-state degree of freedom and their combinations in the wave function as well as in the real-space configuration. Present results provide a possible interpretation for the recent experimental observation under the strong magnetic field in LaCoO 3 . KEYWORDS: spin state, magnetic field, excitonic insulatorSpin-state degree of freedom (SSDF) in the transitionmetal ions have been widely recognized as one of the indispensable factors which provide rich variety of physics in magnetic solids. There are multiple spin states in a single magnetic ion due to the different local electron configurations. Transitions between the multiple spin states are often seen in the iron and cobalt ions which are included not only in correlated electron materials, 1-3) but also in biomaterials, 4) and earth innercore materials. 5-7) A driving force of the spin-state transition is attributed to a competition between the crystalline-field effect and the Hund's coupling, which stabilize the low-spin (LS) and high-spin (HS) states, respectively. 8,9) Perovskite cobalt oxides and their derivatives are the prototypical examples of the correlated electron materials with SSDF. A nominal valence of the cobalt ion in LaCoO 3 is 3+ where the number of electrons occupying the 3d orbitals is six. The characteristic temperature dependences of the electrical resistivity and the magnetic susceptibility are interpreted as a crossover between the LS state of the (t 2g ) 6 configuration with S = 0 and the HS states of (t 2g ) 4 (e g ) 2 with S = 2. 2) Several exotic phenomena, such as the giant magnetoresistance, 10) magnetic clusters, 11,12) and a ferroelectricity, 14) are attributable to the spin-state change.Correlated electron materials with SSDF is recently reexamined as a plausible candidate of the excitonic insulator (EI). [15][16][17] The EI state has been studied since 1960s in the narrow gap semiconductors and semimetals, [18][19][20][21][22] and is recently reexamined from the modern viewpoints. 23,24) The EI state is expected to be realized, when the exciton binding energy exceeds the band gap energy. Since the LS and HS states in the cobalt oxides are identified as a band insulator and a Mott insulator, respectively, a narrow-gapped state is expected around a crossover between the two spin states. Actually, a phase transition around 90K observed in Pr 0.5 Ca 0.5 CoO 3 is examined from the viewpoints of the EI phase transition. 16) It is required to develop how to control the spin states ...

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Temperature- and pressure-induced spin-state transitions inLaCoO3

Cited by 182 publications

References 57 publications

Probing the 3d Spin Momentum with X-ray Emission Spectroscopy: The Case of Molecular-Spin Transitions

Probing the 3d Spin Momentum with X-ray Emission Spectroscopy: The Case of Molecular-Spin Transitions

Evidence of Mott physics in iron pnictides from x-ray spectroscopy

Magnetic Field Effects in a Correlated Electron System with Spin-State Degree of Freedom — Implications for an Excitonic Insulator —

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