{'fraction_non_alphanumeric': 0.01695906432748538, 'fraction_numerical': 0.012280701754385965, 'mean_word_length': 5.154676258992806, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 1, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Weak ferromagnetism and spin-glass behaviour of the n = 3 Ruddlesden-Popper compound Ca4Mn3O10: a dc magnetization study

We present a detailed dc magnetization study of the compound Ca4 Mn3 O10 , which undergoes a transition into a G-type antiferromagnetic structure on cooling below 113.5 K. A series expansion analysis of the magnetic susceptibility shows the material behaves as a quasi-2D antiferromagnet in the temperature regime above TN . This is corroborated by the analysis of the thermal evolution of the spontaneous magnetization obtained from neutron diffraction data. The antiferromagnetic transition is accompanied by the appearance at non-zero field of a net ferromagnetic moment of the order of 10-3 µB . This parasitic ferromagnetism is ascribed to a Dzyaloshinskii-Moriya term arising from the orthorhombic distortion of the crystal structure. The resulting weak ferromagnetic component in each MnO2 layer is hidden at zero field but an applied magnetic field induces a spin-flop transition to a phase with a net magnetization. A non-zero moment is observed at temperatures well above the antiferromagnetic transition and may be responsible for the negative magnetoresistance, which persists to >200 K. The behaviour below TN is dependent on the annealing treatment of the sample. Thermoremanent magnetization (TRM) measurements indicate a complex behaviour below the transition. TRM decay curves at low temperatures have been fitted to a stretched exponential function characteristic of spin glasses. The origin of this disordered behaviour may lie in the inhomogeneous distribution of the distortion that gives rise to the weak ferromagnetic phase, or in the detailed nature of that phase.