Exotic hysteresis of ferrimagnetic transition in Laves compound TbCo₂

We observed exotic hysteresis behavior in the ferrimagnetic transition of a Laves compound TbCo₂. While positive thermal hysteresis was observed in zero-field calorimetric measurements, inverse thermal hysteresis was observed in thermomagnetic measurements as a rare phenomenon. These observations confirmed a first order of the ferrimagnetic transition and revealed a lowering of this order by an external magnetic field. Elastic measurements and high-resolution synchrotron X-ray diffraction measurements suggested that the rare inverse thermal hysteresis can be related to microscopic lattice strains. Those strains are induced by a spontaneous magnetoelastic coupling and are modified by the external magnetic field. IMPACT STATEMENT: This work has reconciled discrepancies about the order of the ferrimagnetic transition of a Laves compound TbCo₂ by observations of field-dependent thermal hysteresis, including rare inverse thermal hysteresis.