Far Infrared Laser Spectroscopy of Spin-Clusters in the Linear Ising System CoCl2:2H2O

摘要

A far infrared HCN/DCN laser source and high field superconducting solenoid were used to perform high resolution swept-field spectroscopy of the linear chain magnetic system Co2.2H2O ('CC2'). The field dependent transmission of CC2 was measured at 29.7, 32.2, 51.4 and 52.7/cm over the temperature range 1.3 to 15K in applied fields of from zero to over 100 KOe. The relatively high output power and extreme monochromaticity of the laser source allowed for a qualitative improvement in the resolution of the 'spin-cluster' resonance spectrum and the accurate determination of linewidths and intensities over a substantial temperature range. Spin-cluster excitations corresponding to the creation of 'multimagnons' of effective size up to 14 adjacent flipped spins, with corresponding g-values as large as 95, have been clearly observed. Nearly complete even/odd-cluster manifold separation according to radiation polarization type was obtained. Data taken with the deuterated form of CC2 indirectly verified the existence of an optic phonon at about 29/cm, using its strong coupling to the ordinary 'spin-wave' excitation. A set of new, weak resonances was observed in the middle field region of the spectrum using the HCN laser lines.