Abstract
Although abundant research has focused recently on the quantum criticality of itinerant magnets, critical phenomena of insulating magnets in the vicinity of critical endpoints (CEP's) have rarely been revealed. Here we observe an emergent CEP at 2.05 T and 2.2 K with a suppressed thermal conductivity and concomitant strong critical fluctuations evident via a divergent magnetic susceptibility (e.g., chi ''(2.05 T, 2.2 K)/chi ''(3 T, 2.2 K)/ approximate to 23, 500%, comparable to the critical opalescence in water) in the hexagonal insulating antiferromagnet HoMnO3. DOI: 10.1103/PhysRevLett.110.157202