Weak ferromagnetism induced by pressure in Yb0.8Y0.2InCu4 Original Research Article

We measured magnetization of Yb0.8Y0.2InCu4 as a function of temperature down to 0.6 K, pressure up to 1.2 GPa and magnetic field up to 9 T in order to investigate what kind of ground state is realized in the high-temperature (HT) phase of YbInCu4. It is found that applying pressure of P≥0.8 GPa collapses the valence transition and induces weak ferromagnetism at the lowest temperature in Yb0.8Y0.2InCu4. 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 0.05μB/Yb, although a Yb ion is in the tri-valent state. Some itinerancy in magnetism may play a key role in the ferromagnetism and the valence transition.