Masayoshi Fujihala

Investigation of the Multiferroic Transition in CuO Single Crystal using Dielectric and Raman Spectroscopy Measurements

Single Crystal using Dielectric and Raman Spectroscopy Measurements Dongdong MENG, Xu-Guang ZHENG, Xingliang XU, Jun NAKAUCHI, Masayoshi FUJIHALA, Xiaodong LIU, Qixin GUO, Makoto MAKI 1 Department of Physics, Graduate School of Science and Engineering, Saga University, Saga 840-8502, Japan 2 Department of Physics, Faculty of Science and Engineering, Saga University, Saga 840-8502, Japan Department of Physics, College of Science, Tianjin Polytechnic University, Tianjin 300387, China Synchrotron Light Application Center & Department of Electrical and Electronic Engineering, Saga University, Saga 840-8502, Japan

Raman Band Redshifting of α-Cu2(OH)3Cl with Decreasing the Temperature

Raman spectra of the magnetic geometric frustration material – the botallackite-structure α-Cu2(OH)3Cl polycrystalline sample were measured down to liquid N2 temperature. It is found that the hydroxyl stretching bands shift abnormally according to the lattice thermal expansion effect of normal materials, i.e., they redshift with decreasing the sample temperature (negative thermal expansion) using liquid N2 cooling while other bands blueshift. This abnormality was also confirmed by observing the band-shifting caused by local laser heating effect using different laser powers, and can be qualitatively explained by checking the local hydroxyl environment with a trimeric hydrogen bond.

Raman Spectral Properties of β-Co2(OH)3Cl down to the Liquid Nitrogen Temperature

Raman spectra of the geometrically frustrated material sample β-Co2(OH)3Cl have first, to the best of our knowledge, been measured down to liquid nitrogen temperature using the experimental conditions of 10X-objective @ 60 mW and 50X-objective @ 5 mW, respectively. It is found that most Raman bands blueshift with decreasing the sample temperature, agreeing with the thermal expansion effect of common materials, but the Raman spectra from different experimental conditions are slightly different with each other at same temperatures. The difference between them has been explained by the local laser heating effect.