A 169Tm-Mِssbauer spectroscopy investigation of orthorhombic phase

AC susceptibility and specific heat measurements confirm that the Mn sub-lattice of o-TmMnO3 orders at T N M n ≈ 41 K with a weaker feature at T C ≈ 32 K . 169Tm-Mössbauer spectra are interpreted in terms of a single, asymmetric, quadrupole-split doublet whose line width increases sharply at T C . This suggests the presence of a weak induced Tm-site moment, consistent with claims that the Mn sub-lattice magnetism undergoes a transition from incommensurate to collinear antiferromagnetic order at this temperature.