Spectroscopic Signature of Spin-Charge-Lattice Coupling in CuB2O4

Rea Divina Mero, Chun Hao Lai, Chao Hung Du, Hsiang Lin Liu*


研究成果: 雜誌貢獻期刊論文同行評審


CuB2O4 has attracted considerable attention because of its unique chemical and physical properties and potential practical applications. In this paper, we investigated the optical properties of CuB2O4 single crystals through spectroscopic ellipsometry and Raman scattering spectroscopy. The optical absorption spectrum at room temperature revealed a direct band gap at approximately 3.88 ± 0.01 eV and two bands near 4.49 and 5.90 eV. The observed bands were related to charge transfer of electrons from the 2p states of the oxygen ions to the 3d states of the copper ions. The band gap exhibited unusual redshift with a decrease in temperature. Upon cooling across 21 K, which is the canted antiferromagnetic ordering temperature, the band gap, peak energy, and normalized intensity of charge-transfer bands presented anomalies. Furthermore, 38 phonon modes were identified in the room-temperature Raman scattering spectrum of CuB2O4. The phonon modes at approximately 335, 393, 403, 445, 473, 598, 706, 787, and 900 cm-1 exhibited softening below 21 K. The spin-phonon coupling constants were estimated to be 0.02-0.03 cm-1. These findings highlight a complex nature of spin-charge-lattice interactions in CuB2O4.

頁(從 - 到)4322-4329
期刊Journal of Physical Chemistry C
出版狀態接受/付印 - 2021

ASJC Scopus subject areas

  • 電子、光磁材料
  • 能源(全部)
  • 物理與理論化學
  • 表面、塗料和薄膜


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