Electron Spin Resonance (ESR) and Microwave Absorption Studies in TbMnO Multiferroic Compound

We report temperature dependent X-Band (f~9.5 GHz) Electron Spin Resonance (ESR) and microwave absorption measurements in a single crystal of TbMnO₃. A single Lorentzian ESR line with an isotropic g-value g~1.96 was observed for Tges120 K up to 600 K. The ESR signal is attributed to the Mn³⁺ ions in a insulator environment. The temperature dependence of the ESR linewidth is investigated for the external field applied along the three crystallographic axes. For all direction the ESR linewidth show a strong broadening as the temperature decreases due to the presence of short range magnetic correlations. The microwave absorption around the ferroelectric transition T_lock~27 K was investigated using a special cavity with a TE₁₀₃ mode where the sample sits at the maximum microwave electric-field