Quantum criticality in the anisotropic spin-chain antiferromagnet Ca2CoH2(SeO3)4

Abstract

The quantum criticality of an XXZ-type spin chain antiferromagnet Ca2⁢CoH2⁢(SeO3)4, subjected to an external magnetic field, was investigated through ultralow-temperature specific heat, magnetocaloric effect, and magnetic susceptibility measurements. In the absence of an external magnetic field, the system undergoes an antiferromagnetic phase transition at 𝑇𝑁=1.42K. The application of an external field gradually suppresses the antiferromagnetic order. Furthermore, an additional phase emerges in the intermediate field range when the zero-field antiferromagnetic order is suppressed, resulting in a quantum critical point at 𝐵𝑠≈2.55T. Near this field-induced quantum critical point, universal scaling behaviors are observed, characterized by the universality class parameters 𝑑=1, 𝜈=1/2, and 𝑧=2.