Quantum criticality in geometrically frustrated Ho_2Ti_2O_7 and Dy_2Ti_2O_7 spin ices

摘要

Geometrically frustrated magnetic materials possess multiple exotic states associated by lattice architecture induced competing magnetic interactions. It has been found that in case of Ho2Ti2O7, where quantum critical region existed up to similar to 28.5 K, both single ion spin freezing (T-f)and spin ice freezing (T-ice)follows the (H - Hc)(1/2) variation with different values of the critical field. Where as in case of Dy2Ti2O7, it follows a liner relation. Accordingly, a H-T phase diagram, for this spin freezing phenomenon, has been presented for these compounds. The studies on magnetically distorted Ho2Ti1.9 Mn0.1O7 & Dy2Ti1.9 Mn0.1O7 compounds, lead us to conclude that competing magnetic interactions acting in different temperature regime are one of the preliminary factors responsible for the alteration in quantum critical point. These results provide a new platform for the experimental investigation and description of multiple exotic states occurring in frustrated magnets in term of quantum criticality.