Electronic structure changes across the valence transition in EuNi 2(Si0.2Ge0.8)2

P. A. Rayjada, A. Chainani, K. Kanai, T. Haruna, Takayoshi Yokoya, S. Shin, H. Wada, M. Shiga

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

We study the electronic structure of EuNi2(Si 0.2Ge0.8)2, which exhibits a temperature dependent mixed valence transition, using 4d-4f resonant photoemission spectroscopy (RESPES), x-ray absorption spectroscopy (XAS) and temperature-dependent ultraviolet photoemission spectroscopy (UPS). The RESPES studies identify the divalent and trivalent Eu 4f character density of states (DOS) which participate in the valence transition. Using the photoionization cross section variation as a function of photon energy, we discuss the Eu, Ni, and Ge-Si partial DOS in the valence band. The bulk divalent Eu 4f character states are centered at a binding energy of about 0.75 eV, significantly away from the Fermi level. While the surface divalent feature is negligibly affected, the spectra obtained using He IIα UPS exhibit temperature dependent bulk Eu 4f character states. The bulk divalent spectral weight is transferred to the high energy trivalent states, across the valence transition temperature, T υ ∼ 80 K. The He Iα UPS also exhibit spectral intensity changes across Tυ. The non-f character conduction band states at and near the Fermi level exhibit spectral weight changes up to 350 meV with a small energy (∼25 meV) temperature dependent pseudogaplike feature. The results suggest an increase in effective hybridization strength between the conduction and 4f electrons in the low temperature nearly trivalent phase. While the 4f character changes across Tυ are qualitatively consistent with change in valence configurations, the temperature dependent spectral changes in the non-f character DOS indicate direct participation in the valence transition in EuNi2(Si 0.2Ge0.8)2.

Original languageEnglish
Pages (from-to)1-7
Number of pages7
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume70
Issue number23
DOIs
Publication statusPublished - Dec 2004
Externally publishedYes

Fingerprint

Electron transitions
Electronic structure
Photoelectron spectroscopy
electronic structure
valence
photoelectric emission
Ultraviolet spectroscopy
spectroscopy
Fermi level
Temperature
temperature
Photoionization
Valence bands
Conduction bands
Binding energy
Absorption spectroscopy
x ray absorption
conduction electrons
Electron energy levels
x ray spectroscopy

ASJC Scopus subject areas

  • Condensed Matter Physics

Cite this

Electronic structure changes across the valence transition in EuNi 2(Si0.2Ge0.8)2. / Rayjada, P. A.; Chainani, A.; Kanai, K.; Haruna, T.; Yokoya, Takayoshi; Shin, S.; Wada, H.; Shiga, M.

In: Physical Review B - Condensed Matter and Materials Physics, Vol. 70, No. 23, 12.2004, p. 1-7.

Research output: Contribution to journalArticle

Rayjada, P. A. ; Chainani, A. ; Kanai, K. ; Haruna, T. ; Yokoya, Takayoshi ; Shin, S. ; Wada, H. ; Shiga, M. / Electronic structure changes across the valence transition in EuNi 2(Si0.2Ge0.8)2. In: Physical Review B - Condensed Matter and Materials Physics. 2004 ; Vol. 70, No. 23. pp. 1-7.
@article{4f93fc71c99644519276ebe8fff761bd,
title = "Electronic structure changes across the valence transition in EuNi 2(Si0.2Ge0.8)2",
abstract = "We study the electronic structure of EuNi2(Si 0.2Ge0.8)2, which exhibits a temperature dependent mixed valence transition, using 4d-4f resonant photoemission spectroscopy (RESPES), x-ray absorption spectroscopy (XAS) and temperature-dependent ultraviolet photoemission spectroscopy (UPS). The RESPES studies identify the divalent and trivalent Eu 4f character density of states (DOS) which participate in the valence transition. Using the photoionization cross section variation as a function of photon energy, we discuss the Eu, Ni, and Ge-Si partial DOS in the valence band. The bulk divalent Eu 4f character states are centered at a binding energy of about 0.75 eV, significantly away from the Fermi level. While the surface divalent feature is negligibly affected, the spectra obtained using He IIα UPS exhibit temperature dependent bulk Eu 4f character states. The bulk divalent spectral weight is transferred to the high energy trivalent states, across the valence transition temperature, T υ ∼ 80 K. The He Iα UPS also exhibit spectral intensity changes across Tυ. The non-f character conduction band states at and near the Fermi level exhibit spectral weight changes up to 350 meV with a small energy (∼25 meV) temperature dependent pseudogaplike feature. The results suggest an increase in effective hybridization strength between the conduction and 4f electrons in the low temperature nearly trivalent phase. While the 4f character changes across Tυ are qualitatively consistent with change in valence configurations, the temperature dependent spectral changes in the non-f character DOS indicate direct participation in the valence transition in EuNi2(Si 0.2Ge0.8)2.",
author = "Rayjada, {P. A.} and A. Chainani and K. Kanai and T. Haruna and Takayoshi Yokoya and S. Shin and H. Wada and M. Shiga",
year = "2004",
month = "12",
doi = "10.1103/PhysRevB.70.235105",
language = "English",
volume = "70",
pages = "1--7",
journal = "Physical Review B-Condensed Matter",
issn = "1098-0121",
publisher = "American Physical Society",
number = "23",

}

TY - JOUR

T1 - Electronic structure changes across the valence transition in EuNi 2(Si0.2Ge0.8)2

AU - Rayjada, P. A.

AU - Chainani, A.

AU - Kanai, K.

AU - Haruna, T.

AU - Yokoya, Takayoshi

AU - Shin, S.

AU - Wada, H.

AU - Shiga, M.

PY - 2004/12

Y1 - 2004/12

N2 - We study the electronic structure of EuNi2(Si 0.2Ge0.8)2, which exhibits a temperature dependent mixed valence transition, using 4d-4f resonant photoemission spectroscopy (RESPES), x-ray absorption spectroscopy (XAS) and temperature-dependent ultraviolet photoemission spectroscopy (UPS). The RESPES studies identify the divalent and trivalent Eu 4f character density of states (DOS) which participate in the valence transition. Using the photoionization cross section variation as a function of photon energy, we discuss the Eu, Ni, and Ge-Si partial DOS in the valence band. The bulk divalent Eu 4f character states are centered at a binding energy of about 0.75 eV, significantly away from the Fermi level. While the surface divalent feature is negligibly affected, the spectra obtained using He IIα UPS exhibit temperature dependent bulk Eu 4f character states. The bulk divalent spectral weight is transferred to the high energy trivalent states, across the valence transition temperature, T υ ∼ 80 K. The He Iα UPS also exhibit spectral intensity changes across Tυ. The non-f character conduction band states at and near the Fermi level exhibit spectral weight changes up to 350 meV with a small energy (∼25 meV) temperature dependent pseudogaplike feature. The results suggest an increase in effective hybridization strength between the conduction and 4f electrons in the low temperature nearly trivalent phase. While the 4f character changes across Tυ are qualitatively consistent with change in valence configurations, the temperature dependent spectral changes in the non-f character DOS indicate direct participation in the valence transition in EuNi2(Si 0.2Ge0.8)2.

AB - We study the electronic structure of EuNi2(Si 0.2Ge0.8)2, which exhibits a temperature dependent mixed valence transition, using 4d-4f resonant photoemission spectroscopy (RESPES), x-ray absorption spectroscopy (XAS) and temperature-dependent ultraviolet photoemission spectroscopy (UPS). The RESPES studies identify the divalent and trivalent Eu 4f character density of states (DOS) which participate in the valence transition. Using the photoionization cross section variation as a function of photon energy, we discuss the Eu, Ni, and Ge-Si partial DOS in the valence band. The bulk divalent Eu 4f character states are centered at a binding energy of about 0.75 eV, significantly away from the Fermi level. While the surface divalent feature is negligibly affected, the spectra obtained using He IIα UPS exhibit temperature dependent bulk Eu 4f character states. The bulk divalent spectral weight is transferred to the high energy trivalent states, across the valence transition temperature, T υ ∼ 80 K. The He Iα UPS also exhibit spectral intensity changes across Tυ. The non-f character conduction band states at and near the Fermi level exhibit spectral weight changes up to 350 meV with a small energy (∼25 meV) temperature dependent pseudogaplike feature. The results suggest an increase in effective hybridization strength between the conduction and 4f electrons in the low temperature nearly trivalent phase. While the 4f character changes across Tυ are qualitatively consistent with change in valence configurations, the temperature dependent spectral changes in the non-f character DOS indicate direct participation in the valence transition in EuNi2(Si 0.2Ge0.8)2.

UR - http://www.scopus.com/inward/record.url?scp=13944260043&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=13944260043&partnerID=8YFLogxK

U2 - 10.1103/PhysRevB.70.235105

DO - 10.1103/PhysRevB.70.235105

M3 - Article

AN - SCOPUS:13944260043

VL - 70

SP - 1

EP - 7

JO - Physical Review B-Condensed Matter

JF - Physical Review B-Condensed Matter

SN - 1098-0121

IS - 23

ER -