We study the mechanism how critical end points of first-order valence transitions are controlled by a magnetic field. We show that the critical temperature is suppressed to be a quantum critical point (QCP) by a magnetic field and unexpectedly the QCP exhibits nonmonotonic field dependence in the ground-state phase diagram, giving rise to emergence of metamagnetism even in the intermediate valence-crossover regime. The driving force of the field-induced QCP is clarified to be cooperative phenomena of Zeeman effect and Kondo effect, which create a distinct energy scale from the Kondo temperature. This mechanism explains peculiar magnetic response in CeIrIn5 and metamagnetic transition in YbXCu4 for X=In as well as sharp contrast between X=Ag and Cd.
@article{arxiv.0804.4734,
title = {Magnetic-Field Control of Quantum Critical Points of Valence Transition},
author = {Shinji Watanabe and Atsushi Tsuruta and Kazumasa Miyake and Jacques Flouquet},
journal= {arXiv preprint arXiv:0804.4734},
year = {2008}
}