Investigating the nature of a geometrically frustrated material: spin-ice

S. A. GRIGERA

Conferencia; Latin-American Webinar of Magnetism; 2021

Geometrically frustrated magnetic materials, where the symmetry precludes the possibility ofsatisfying every pairwise interactions, are extremely interesting systems from a statisticalmechanical point of view. The competition between different ordering tendencies can inducecomplex and novel phenomena. A particularly notable example of this type of systems are theso-called ?spin-ice? materials, which are an experimental example of fractional magnetic excitationsand emergent Coulomb-like interactions.Spin-ice materials owe their name to their analogy with water ice. The ?ice-rules? that the groundstate must obey are the very origin of the emergent gauge structure. The theory predicts amacroscopically disordered state with Pauling?s residual entropy. Additional interactions, such as adipolar term, are expected to break this degeneracy and order the system at sufficiently lowtemperature. Yet, no evidence of long range order has been found, and the true nature of the groundstate of spin-ice systems remains a mystery, which the extremely rapidly growing characteristictimes shroud into further obscurity.The idea of this talk is to give a general introduction to thisvproblem and class of materials and todiscuss some of the tools used to investigate their nature, including diffuse neutron scattering, heatcapacity, susceptibility and noise measurements, and theoretical and computational analysis,including machine learning techniques.