High-field magnetization and magnetic structure of Tb₃Co

Abstract

The measurements of the magnetization in high steady and pulsed fields together with neutron diffraction measurements on a powder sample and on a single crystal have been performed to study the magnetic state of the Tb 3 Co compound. It has been shown that the modulated antiferromagnetic structure which exists in Tb 3 Co below T N = 82 K transforms to the incommensurate magnetic structure with a strong ferromagnetic component along the c-axis with further cooling below the critical temperature T t ≈ 72 K. The phase transition from the high-temperature to the low-temperature magnetic state at T t is of first order. The incommensurability of the low-temperature magnetic structure of Tb 3 Co is attributed to the non-Kramers character of the Tb 3+ ion in combination with competition between the indirect exchange interaction and the low-symmetry crystal electric field.

Effect of rapid quenching on the magnetic state, electrical resistivity and thermomagnetic properties of Gd3Co

“…Meanwhile, the Curie temperatures of other rapidly quenched R 3 Co alloys (R ¼ Nd, Tb, Dy) [17] are observed to be close to the magnetic ordering temperatures for their polycrystalline counterparts [7,18,19]. As was mentioned above, the gain in the exchange energy in the amorphous Gd 3 Co alloy was suggested to result from the appearance of a magnetic moment on Co atoms.…”

Field-induced magnetic phase transitions and metastable states in Tb3Ni

“…Among the rare-earth intermetallic compounds, R 3 T (T = Co, Ni) compounds possess the highest content of rare-earth metal within the binary R − T systems and exhibit a rich variety of physical properties: unconventional superconductivity [7,8], charge density wave [9], giant magnetoresistance effect [10,11], multi-component magnetic structures exhibiting coexistence of commensurate and incommensurate propagation vectors [12,13], field-induced magnetic phase transitions [13][14][15][16] and giant magnetocaloric effect [17][18][19][20]. R 3 T compounds crystallize in a low-symmetry orthorhombic structure of the Fe 3 C type described with the space group P nma [21].…”

Single-crystal neutron diffraction study of the magnetic structure ofEr3Co

“…The commensurate magnetic structures ͑although, different from Er 3 Co case͒ were also found in other R 3 Co compounds with Kramerstype ions, R = Dy and Nd. 3,11 This is in contrast to the incommensurate magnetic structure established for the systems with non-Kramers rare earth, e.g., Ho 3 Co and Tb 3 Co. 5,6 The type of the magnetic structure within R 3 Co series can be understood on the base of the periodic field model which takes into account the periodic exchange field and CEF effects. 12 According to this model an incommensurable magnetic structure may be observed down to low temperatures when a non-Kramers R 3+ ion has a nonmagnetic singlet ground state due to splitting of the multiplet by lowsymmetry CEF.…”

“…However, more recent studies using new generation of neutron-scattering techniques have revealed that some of R 3 Co͑R =Ho, Tb͒ compounds exhibit much more complex magnetic structures. 5,6 The structures turn out to be incommensurate not only just below the magnetic ordering point but down to the lowest temperatures as well. We proposed recently that the non-Kramers character of the rare-earth ions is responsible for the incommensurability of the magnetic structures of these R 3 T compounds at low temperatures.…”

“…We proposed recently that the non-Kramers character of the rare-earth ions is responsible for the incommensurability of the magnetic structures of these R 3 T compounds at low temperatures. 6 To our best knowledge, the only neutron powder diffraction study of the Er 3 Co magnetic structure was done by Gignoux et al 1 They found that the magnetic structure is commensurate ͑Er being a Kramers ion͒ and noncollinear with a ferromagnetic component along the b axis. Magnetic moments of Er ions in 4c sites are suggested to be aligned strictly along the b direction, while in 8d positions the moments have a deviation from the b axis in such a manner that their projections along a and c axes are ordered antiferromagnetically.…”