Growth and characterization of perovskite TbMnO3 single crystal: Structural, vibrational and magnetic properties

Abstract

In this study, we have successfully grown a high-quality single crystal of perovskite TbMnO3 utilizing an optical floating zone furnace under an air atmosphere. To ensure the crystal purity and orientation, we probed X-ray diffractometer (XRD) and X-ray Laue photographic analysis, respectively. The XRD analysis confirmed that TbMnO3 ceramics possess a distorted orthorhombic perovskite structure (Pbnm). By analyzing the X-ray absorption and vibrational modes via Raman spectroscopy, we not only confirmed the pure phase of the TbMnO3 sample but also gained valuable insights. In terms of magnetic properties, we conducted measurements in two different orientations: H||a and H||c. Notably, there were no successive transitions observed along the H||a direction, but along H||c, we observed three successive transitions with decreasing temperature at TN = 41 K, TS = 28 K, and TNTb = 7 K. Below TN (41 K), there is an unusual softening observed in one of the first order phonon modes, indicating a robust connection between spin and phonon interactions. The magnetic phase transition along both axes validates the presence of magnetic anisotropy in the prepared single crystal, as indicated by magnetic susceptibility. The negative θcw value along the a-axis and the positive θcw value along the c-axis suggest a competition between antiferromagnetic and ferromagnetic interactions in the ac-plane.