Optical Study of the Electronic Structure and Lattice Dynamics of NdBaMn2O6 Single Crystals

• Published in: Scientific reports Vol. 9; no. 1; pp. 1 - 11
• Main Authors: Mero, Rea Divina, Ogawa, Kirari, Yamada, Shigeki, Liu, Hsiang-Lin
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 03.12.2019; Nature Publishing Group
• Subjects: 639/301; 639/301/119; Crystals; Humanities and Social Sciences; multidisciplinary; Phase transitions; Science; Science (multidisciplinary); Single crystals; Spectroscopy
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-019-54524-0

We investigated the electronic structure and lattice dynamics of double perovskite NdBaMn 2 O 6 single crystals through spectroscopic ellipsometry and Raman scattering spectroscopy. The optical absorption band centered at approximately 0.88 eV was assigned to on-site d – d transitions in Mn, whereas the optical feature at approximately 4.10 eV was assigned to charge-transfer transitions between the 2 p state of O and 3 d state of Mn. Analysis of the temperature dependence of the d-d transition indicated anomalies at 290 and 235 K. The activated phonon mode, which appeared at approximately 440 cm −1 alongside with the enhancement of the 270 cm −1 phonon mode, coupled strongly to the metal–insulator transition at 290 K, which was associated with a charge/orbital ordering. Moreover, the MnO 6 octahedral breathing mode at 610 cm −1 exhibited softening at a temperature lower than 235 K (temperature of the antiferromagnetic phase transition), which revealed the strong coupling between the lattice and magnetic degrees of freedom. The spin–phonon coupling constant obtained was λ = 2.5 cm −1 . These findings highlight the importance of charge–orbital–spin interactions in establishing NdBaMn 2 O 6 phases with novel properties.