Electronic structure and lattice dynamics of Li2Ni(WO4)2

Yun Chen Chung, Sunil K. Karna, Fan Cheng Chou, Hsiang Lin Liu

Research output: Contribution to journalArticle

Abstract

We combined spectroscopic ellipsometry and Raman scattering measurements to explore the electronic structure and lattice dynamics in Li2Ni(WO4)2. The optical absorption spectrum of Li2Ni(WO4)2 measured at room temperature presents a direct optical band gap at 2.25 eV and two bands near 5.2 and 6.0 eV, which are attributed to charge-transfer transitions from oxygen 2p states to nickel 3d or tungsten 5p states. The Raman scattering spectrum of Li2Ni(WO4)2 measured at room temperature presents seventeen phonon modes at approximately 112, 143, 193, 222, 267, 283, 312, 352, 387, 418, 451, 476, 554, 617, 754, 792, and 914 cm−1. When the temperature is decreased to 20 K, the frequency, linewidth, and normalized intensity of all phonon modes exhibited almost no temperature dependence. Upon cooling across 13 K, which is the antiferromagnetic phase transition temperature, the oxygen octahedra stretching mode at 914 cm−1 exhibited a softening and an increase in intensity, thus suggesting a coupling between the magnetic and lattice degrees of freedom. The spin-phonon coupling constant was estimated to be 0.94 mRy/Å2, indicating a weak spin-phonon interaction in Li2Ni(WO4)2.

Original languageEnglish
Pages (from-to)473-480
Number of pages8
JournalChinese Journal of Physics
Volume60
DOIs
Publication statusPublished - 2019 Aug

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Keywords

  • Optical spectroscopy
  • Spin-phonon coupling
  • Strongly correlated electron system

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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