Valence transition induced by pressure and magnetic field in antiferromagnet EuRh₂Si₂

We report the effects of a magnetic field on a pressure-induced valence transition in EuRh₂Si₂ by using magnetization measurements under high pressure. The M-H curves at 2 K under various pressures up to 1.18 GPa exhibit no anomalies associated with a field-induced valence transition. On the other hand, the M-H curves under a pressure of ∼ 1 GPa, where a temperature-induced valence transition occurs at around 30 K, show a clear metamagnetic transition with a large hysteresis at around 30 K. This behavior corresponds to a field-induced valence transition. The M-T curves in magnetic fields indicate that with increasing magnetic field, the temperature-induced valence transition shifts toward lower temperature and that its thermal hysteresis becomes larger. Cooling the sample under a pressure of ∼ 1 GPa in a magnetic field of 7 T collapses the valence transition and stabilizes the magnetic high-temperature phase down to 2 K. Besides, with decreasing magnetic field, three sharp valence transitions toward the nonmagnetic Eu³⁺ direction are observed: 4.65, 2.65 and 1.93 T.