OPTICAL-ABSORPTION BANDS BY EXCITON-MAGNON COUPLING IN QUASI-TWO-DIMENSIONAL ANTIFERROMAGNETS (CNH2N+1NH3)(2)MNCL4 (N=1,2,3)

摘要

Absorption spectra of layer-structured (CnH2n+1NH3)(2)MnCl4 with n = 1 (abbreviated MAMC), n = 2 (EAMC), and n = 3 (PAMC) have been investigated in the uv-to-visible light region at temperatures of 15-300 K. In addition to the single-exciton and double-exciton bands caused by the magnetic interaction, an absorption band whose intensity is given by both the two-dimensional magnetic interaction and lattice vibration was found. A sharp magnon sideband with double peaks was observed in EAMC and PAMC. The peak distance is smaller in EAMC than in PAMC. On the other hand, a single peak was observed in MAMC. It is suggested that the splitting of the magnon sideband is caused by the weak ferromagnetism due to spin canting in the layer. The line shape of the magnon sideband is calculated and compared with the observed ones. [References: 24]