Collapse of Valence Transition in [Formula presented]: Pressure-Induced Weak Ferromagnetism

We investigated the magnetization of [Formula presented] as a function of temperature down to 0.6 K, pressure up to 1.2 GPa, and magnetic field up to 9 T. The valence transition temperature of [Formula presented] is lowered with applying pressure. At 0.8 GPa, collapse of the valence transition and ferromagnetic ordering occur almost simultaneously. The ferromagnetic phase at 1.2 GPa is characterized by a low Curie temperature of 1.7 K and an extremely small ordered moment of [Formula presented] per Yb. Some effect of screening the ordered moment may play a key role in the ferromagnetism and the valence transition.