Photoemission study of the temperature-dependent energy-gap formation in the Kondo semiconductor CeRhAs

Shimada, Kenya; Higashiguchi, M.; Narimura, Takamasa; Arita, Masashi; Takeda, Yukiharu; Namatame, H.; Takeuchi, Masaki; Sasakawa, Tetsuya; Suemitsu, Toshimitsu; Takabatake, Toshiro

doi:10.1016/j.elspec.2005.01.148

Cited by 5 publications

(6 citation statements)

References 15 publications

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“…With increasing T , the pseudogap structure is found to be smeared, and then finally disappears at high temperature above the so-called coherence temperature T 0 , where the T dependence of ρ f (ǫ) is mainly caused by the evolution of the imaginary part of the self-energy ImΣ(ǫ) that becomes large for T > ∼ T 0 as explicitly shown in Sec. III C. Such T dependence of ρ f (ǫ) has been observed in the tunneling 16 and photoemission 23,24 spectroscopies for the Kondo semiconductors.…”

Section: Results For H =mentioning

confidence: 55%

“…A remarkable feature of the anisotropic Kondo semiconductors is the significant temperature dependence of the pseudogap. In the tunneling 16 and the photoemission spectroscopies, 23,24 the pseudogap in the DOS is clearly observed at low temperature, while it vanishes at high temperature. Such temperature dependent pseudogap cannot be explained with a simple rigid-band model.…”

Section: Introductionmentioning

confidence: 94%

“…15,[49][50][51] The PAM with the kdependent c-f mixing has been studied by using the Gutzwiller approximation 15 and the slave-boson meanfield theory, 49 which reproduce the highly reduced pseudogap and well explain the thermodynamic and transport properties of the anisotropic Kondo semiconductors at low temperature. However, the temperature dependence of the pseudogap, which is directly observed in the tunneling and photoemission spectroscopies, 16,23,24 together with the magnetic field dependence was not discussed there.…”

Section: Introductionmentioning

confidence: 99%

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Dynamical mean-field theory for the anisotropic Kondo semiconductor: Temperature and magnetic field dependence

Yamada

Ōno

2012

Phys. Rev. B

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We investigate the periodic Anderson model with k-dependent c-f mixing reproducing the point nodes of the hybridization gap by using the dynamical mean-field theory combined with the exact diagonalization method. At low temperature below a coherence temperature T0, the imaginary part of the self-energy is found to be proportional to T 2 and the pseudogap with two characteristic energies∆1 and∆2 is clearly observed for T ≪ T0, while the pseudogap is smeared with increasing T and then disappears at high temperature T > ∼ T0 due to the evolution of the imaginary self-energy. When the Coulomb interaction between f electrons U increases,∆1,∆2, and T0 together with Tmax at which the magnetic susceptibility is maximum decrease in proportion to the renormalization factor Z resulting in a heavy-fermion semiconductor with a large mass enhancement m * /m = Z −1 for large U . We also examine the effect of the external magnetic field H and find that the magnetization M shows two metamagnetic anomalies H1 and H2 corresponding to∆1 and∆2 which are reduced due to the effect of H together with Z. Remarkably, Z −1 is found to be largely enhanced due to H especially for H1 < ∼ H < ∼ H2, where the field induced heavy-fermion state is realized. The obtained results seem to be consistent with the experimental results observed in the anisotropic Kondo semiconductors such as CeNiSn. * takemi@phys.sc.niigata-u.ac.jp 1 A. C. Hewson, The Kondo Problem to Heavy Fermions (Cambridge University Press, 1993). 2 J. W. Allen, B. Batlogg, and P. Wachter, Phys. Rev. B,

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Section: Results For H =mentioning

confidence: 55%

Section: Introductionmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

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Dynamical mean-field theory for the anisotropic Kondo semiconductor: Temperature and magnetic field dependence

Yamada

Ōno

2012

Phys. Rev. B

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“…A peak structure near E F for x ¼ 0 sample at hn ¼ 881 eV corresponds to the Ce4f 1 final state, which exhibits a hybridization gap of $100 meV. Our previous measurements indicate that the energy gap is originated from As4p, Rh4d and Ce4f hybridization [4,5], in agreement with the band-structure calculation [6]. A broad spectral feature at $2.5 eV is derived from the Ce4f 0 final state and partly from the Rh4d states.…”

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confidence: 98%

High-resolution photoemission study of Ce1−xLaxRhAs: A collapse of the energy gap in the Kondo semiconductor

Shimada

Higashiguchi

Fujimori

et al. 2006

Physica B: Condensed Matter

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High-resolution resonance-photoemission spectroscopy has been performed on the Ce 1Àx La x RhAs (0pxp0.05) single crystal to elucidate a collapse of the energy gap in the Kondo semiconductor CeRhAs by La substitution. With increasing x, the spectral intensity of the Ce4f 1 derived states near the Fermi level decreases and new 4f derived spectral feature appears at a higher binding energy. The Rh4d-derived states, on the other hand, are not significantly changed by the substitution. New 4f-derived states have incoherent nature, which is responsible for the collapse of the semiconducting state for x4$0.02. rThe orthorhombic CeRhAs, known as a Kondo semiconductor, has attracted much interest for its unusual energy-gap formation associated with the successive firstorder-structural-phase transitions [1]. Recently La-substituted Ce 1Àx La x RhAs single crystals have been synthesized [2]. It has been found that a semiconducting behavior almost disappears with a La concentration as low as x$0.02 [2]. In order to elucidate how the energy gap in CeRhAs collapses by the La substitution, we have conducted a high-resolution resonance-photoemission spectroscopy (PES) study of Ce 1Àx La x RhAs (0pxp0.05).Single crystals of Ce 1Àx La x RhAs (x ¼ 0, 0.003, 0.02, 0.05) were grown by the Bridgman method [1,2]. The 3d-4f resonance PES experiments (hn ¼ 870-881 eV) were done at the beamline BL23SU of SPring-8 [3], and the 4d-4f resonance PES experiments (hn ¼ 122 eV) at the beamline BL-1 of HiSOR [4]. The sample temperature was kept at 10-20 K, and the overall energy resolution was set at DE ¼ 20 meV (hn ¼ 122 eV) and 100 meV (hn ¼ 870-881 eV). Clean sample surfaces were obtained by fracturing the sample in the ultrahigh vacuum. Fig. 1 shows on-resonance PES spectra of Ce 1Àx La x RhAs at hn ¼ 881 and 122 eV. Due to large resonance enhancement, one can regard these spectra as the Ce4f partial spectra. We have normalized these spectra to the area for the binding energy (E B ) range of E B $0-9 eV. A peak structure near E F for x ¼ 0 sample at hn ¼ 881 eV corresponds to the Ce4f 1 final state, which exhibits a hybridization gap of $100 meV. Our previous measurements indicate that the energy gap is originated from As4p, Rh4d and Ce4f hybridization [4,5], in agreement with the band-structure calculation [6]. A broad spectral feature at $2.5 eV is derived from the Ce4f 0 final state and partly from the Rh4d states. As the Ce is replaced by La from x ¼ 0 to 0.003, the intensity of the peak near E F is reduced. From x ¼ 0.003 to x ¼ 0.02, a drastic change has been observed; the peak intensity is shifted to the higher binding ARTICLE IN PRESS www.elsevier.com/locate/physb 0921-4526/$ -see front matter r

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“…Fig. 2 shows the valence band HXPES spectra of the Kondo semiconductor CeRhAs and the semimetal CeRhSb, taken at hn$5:95 keV [15], and at hn$40 eV [16]. Below the Kondo temperature, CeRhAs is a metal with a local moment which is responsible for the Kondo effect.…”

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confidence: 99%

Photoemission study of the temperature-dependent energy-gap formation in the Kondo semiconductor CeRhAs

Cited by 5 publications

References 15 publications

Dynamical mean-field theory for the anisotropic Kondo semiconductor: Temperature and magnetic field dependence

Dynamical mean-field theory for the anisotropic Kondo semiconductor: Temperature and magnetic field dependence

High-resolution photoemission study of Ce1−xLaxRhAs: A collapse of the energy gap in the Kondo semiconductor

Hard X-ray valence-band and core-level photoelectron spectroscopy of strongly correlated electron systems

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