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Ice-rule breaking spin-flip in a pyrochlore spin ice compound Dy2Ti2O7 has been studied in a field applied near the [112] direction, by means of angle-resolved magnetization measurements. We obtained strong evidence that the magnetization component perpendicular to the kagom? plane undergoes a first-order transition below ~0.26?K. This transition is driven by a ferromagnetic ordering in the field-decoupled spins on the triangular lattice in Dy2Ti2O7, as predicted theoretically.

We report the first muon-spin relaxation study of an organic spin - Peierls system, the linear-chain compound MEM(TCNQ). Our results show a crossover from a Gaussian relaxation to an exponential relaxation as the temperature is lowered below the spin - Peierls transition. We associate this behaviour with the slowing down of the electronic fluctuations resulting from the opening of a gap in the magnetic excitation spectrum.

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 Kagome plane shows a first-order phase transition below 0.27 K. 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 0.52 K in a magnetic field between the (110) and (111) directions. This phase transition is related to a breakdown of ferromagnetic Ising spin chains along (1¯ 10) or (¯ 110).

Ice-rule breaking spin flip in the pyrochlore spin-ice compound Dy2Ti2O7 has been studied in a field rotated in the plane, by means of angle-resolved magnetization measurements. The field-angle dependence of the spin flip field Hc(θ) has been obtained. Close to the [111] direction, Hc(θ) exhibits a marked deviation from a nearest-neighbour spin-ice model, suggesting the importance of long-range dipolar interaction and a stability of the kagome ice state.