Abstract
A comprehensive study of the magnetic phase transitions in Tb3Co has been undertaken combining different techniques. Using single crystal neutron diffraction in the paramagnetic state a weak crystal structure distortion from the room temperature orthorhombic structure of the Fe3C type described with the Pnma space group toward structure with lower symmetry has been observed with cooling below 100 K. At 81 K there is a second order phase transition to an antiferromagnetic incommensurate phase with the propagation vector k = (0.155, 0, 0). As derived from thermal diffusivity measurements, the critical exponents for this transition are very close to the 3D-Heisenberg universality class, proving that the magnetic interactions are short-range but with a deviation from perfect isotropy due to crystal field effects. At T2 ≈ 70 K there is another magnetic phase transition to a ferromagnetic state whose character is shown to be weakly first order. The low temperature magnetic state has a non-coplanar ferromagnetic structure with strong ferromagnetic components of Tb magnetic moments along the crystallographic c-axis. The application of an external magnetic field B = 2 T along the c crystallographic axis suppresses the incommensurate antiferromagnetic phase and gives rise to the ferromagnetic phase. The magnetic entropy peak change as well as the refrigerant capacity indicate that Tb3Co is a competitive magnetocaloric material in this temperature range.
Original language | English |
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Article number | 106519 |
Journal | Intermetallics |
Volume | 111 |
DOIs | |
State | Published - Aug 2019 |
Funding
This work has been supported by Universidad del País Vasco UPV/EHU ( GIU16/93 ). A. Herrero thanks the Department of Education of the Basque Government as grantee of the programme “Programa Predoctoral de Formación de Personal Investigador No Doctor”. The authors thank for technical and human support provided by SGIker of UPV/EHU. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences , under contract number DE-AC05-00OR22725 . Part of this work was performed at SINQ, Paul Scherrer Institute, Villigen, Switzerland. This work has been supported by Universidad del País Vasco UPV/EHU (GIU16/93). A. Herrero thanks the Department of Education of the Basque Government as grantee of the programme “Programa Predoctoral de Formación de Personal Investigador No Doctor”. The authors thank for technical and human support provided by SGIker of UPV/EHU. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under contract number DE-AC05-00OR22725. Part of this work was performed at SINQ, Paul Scherrer Institute, Villigen, Switzerland. This work was also supported by Russian Science Foundation (project No. 18-72-10022). This work was also supported by Russian Science Foundation (project No. 18-72-10022 ).
Funders | Funder number |
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Office of Basic Energy Sciences | |
Universidad del País Vasco UPV/EHU | GIU16/93 |
U.S. Department of Energy | DE-AC05-00OR22725 |
Office of Science | |
Euskal Herriko Unibertsitatea | |
Russian Science Foundation | 18-72-10022 |
Keywords
- Critical behavior
- Magnetocaloric effect
- Neutron diffraction
- Spin-ordering
- TbCo
- Thermal diffusivity