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arXiv · 0812.4330

On the ferromagnetic structure of the intermetallic borocarbide TbCo2B2C

M. ElMassalami·R. Moreno·R. M. Saeed·F. A. B. Chaves·C. M. Chaves·H. Takeya·B. Ouladdiaf·M. Amara
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Abstract

Based on magnetization, specific heat, magnetostriction, and neutron diffraction studies on single-crystal TbCo2B2C, it is found out that the paramagnetic properties, down to liquid nitrogen temperatures, are well described by a Curie-Weiss behavior of the Tb+3 moments. Furthermore, below Tc= 6.3 K, the Tb-sublattice undergoes a ferromagnetic (FM) phase transition with the easy axis being along the (100) direction and, concomitantly, the unit cell undergoes a tetragonal-to-orthorhhombic distortion. For fields up to 90 kOe, no field-induced splitting of the Co 3d orbitals was observed; as such the internal field must be well below the critical value needed to polarize the Co 3d subsystem. The manifestation of a FM state in TbCo2B2C is unique among all other isomorphous borocarbides, in particular TbNi2B2C (Tn=15 K, incommensurate modulated magnetic state) even though the Tb-ions in both isomorphs have almost the same crystalline electric field properties. The difference in the magnetic modes of these Tb-based isomorphs is attributed to a difference in their exchange couplings caused by a variation in their lattice parameters and in the position of their Fermi levels.

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M. ElMassalami, R. Moreno, R. M. Saeed, F. A. B. Chaves, C. M. Chaves, H. Takeya, B. Ouladdiaf, M. Amara. 2008-12-23. On the ferromagnetic structure of the intermetallic borocarbide TbCo2B2C. https://arxiv.org/abs/0812.4330

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