Low temperature and field studies on the spin ice materials Dy2Ti2O7 and Ho2Ti2O7

PILI, L.; BORZI, R. A.; HICKS, C.; SLOBINSKY, D.; STEPPKE, A.; GURUCIAGA, P. C,; GRIGERA, S. A.

Buenos Aires

Conferencia; 27th International Conference on Statistical Physics; 2019

Departamento de Física, FCEyN-UBA

Spin ice materials, of which Dy_2Ti_2O_7 and Ho_2Ti_2O_7 are usual examples, are geometrically frustrated magnetic systems. Their defining property is the lack of order at the lowest temperatures, leading to an effective residual entropy quite similar to that measured in common water ice. A magnetic field has a profound effect on the magnetism of Spin Ice, on account of the big magnetic moments of Dy^+3 and Ho^+3 ions, and pronounced local anisotropy. It can thus be used to produce other types of partially or totally ordered structures of varying dimensionallity, through crossovers, or conventional and topological phase transitions. In this work we study the dynamics and thermodynamics of these materials using magnetisation and ac-susceptibility. The region of interest is that of low temperatures with magnetic fields, applied along [100] and [111] directions. The contrast between this two crystalographic directions, and with numerical simulations, allows for a more controlled approach to the complex system dynamics, and to the Kasteleyn transition which occurs for fields along [100]. Preliminary studies including strain applied through a piezoelectric device, show an increase in susceptibility as a the systems is driven towards a predicted Infinite Order Multicritical transition.