Observation of a novel phase transition induced by a magnetic field in the pyrochlore spin ice compound

We present a novel field-induced phase transition in the spin ice compound Dy₂Ti₂O₇ that is investigated by means of angle-resolved DC magnetization measurements. In the near [112] field, the magnetization component perpendicular to the Kagomé plane shows a first-order phase transition below 0.27K. This transition is driven by a ferromagnetic ordering in the field-decoupled spins on the triangular lattice. Furthermore, we revealed another first-order phase transition below 0.52K in a magnetic field between the [110] and [111] directions. This phase transition is related to a breakdown of ferromagnetic Ising spin chains along or .