title: On the ferromagnetic structure of the intermetallic borocarbide TbCo(2)B(2)C.
abstract: Based on magnetization, specific heat, magnetostriction and neutron-diffraction studies on single-crystal TbCo(2)B(2)C, 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 T(c) = 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-orthorhombic distortion. The manifestation of an FM state in TbCo(2)B(2)C is unique among all other isomorphous borocarbides, in particular TbNi(2)B(2)C (T(N) = 15 K, incommensurate modulated magnetic state) even though the Tb ions in both isomorphs have almost the same crystalline electric field properties. The difference among the magnetic modes of these Tb-based isomorphs is attributed to a difference in their exchange couplings which are in turn caused by a variation in their lattice parameters and in the position of their Fermi levels.
authors.affiliation: Instituto de Fisica, Universidade Federal do Rio de Janeiro, Caixa Postal 68528, 21945-970 Rio de Janeiro, Brazil.
authors.forename: M
authors.initials: M
authors.lastname: Elmassalami
authors.forename: R
authors.initials: R
authors.lastname: Moreno
authors.forename: R M
authors.initials: RM
authors.lastname: Saeed
authors.forename: F A B
authors.initials: FA
authors.lastname: Chaves
authors.forename: C M
authors.initials: CM
authors.lastname: Chaves
authors.forename: R E
authors.initials: RE
authors.lastname: Rapp
authors.forename: H
authors.initials: H
authors.lastname: Takeya
authors.forename: B
authors.initials: B
authors.lastname: Ouladdiaf
authors.forename: M
authors.initials: M
authors.lastname: Amara