Abstract

The quantum criticality of an XXZ-type spin chain antiferromagnet ${\mathrm{Ca}}_{2}{\mathrm{CoH}}_{2}{({\mathrm{SeO}}_{3})}_{4}$, 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 ${T}_{N}=1.42\phantom{\rule{0.28em}{0ex}}\mathrm{K}$. 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 ${B}_{s}\ensuremath{\approx}2.55\phantom{\rule{0.28em}{0ex}}\mathrm{T}$. Near this field-induced quantum critical point, universal scaling behaviors are observed, characterized by the universality class parameters $d=1, \ensuremath{\nu}=1/2$, and $z=2$.