Pressure-Induced Weak Ferromagnetism and Suppression of Valence Transition in Yb Compound

Abstract

We have paid attention to the ground state of the high-temperature magnetic phase of YbInCu₄ which exhibits a first-order valence transition at 42 K. The high-temperature phase, which shows Curie-Weiss paramagnetism of Yb³⁺, is stabilized down to zero temperature by the application of pressure and/or substitution of Y for Yb. We have measured magnetization of Yb_0.8Y_0.2InCu₄ under high pressure in the low temperature ranges down to 0.6 K and could observe suppression of the valence transition and occurrence of ferromagnetism at the same time. The ferromagnetism is characterized by a low Curie temperature of 1.8 K and very small spontaneous magnetization of 0.067 μ_B/Yb.