Magnetic susceptibility, specific heat, and muon spin relaxation ($\mu \mathrm{SR}$) measurements have been performed on a synthesized three-dimensional sandglass-type lattice ${\mathrm{Tm}}_3{\mathrm{SbO}}_7$, where two inequivalent sets of non-Kramers ${\mathrm{Tm}}^{3+}$ ions (${\mathrm{Tm}}_1^{3+}$ and ${\mathrm{Tm}}_2^{3+})$ show crystal electrical field effect at different temperature ranges. The existence of an ordered or a glassy state down to 0.1 K in zero field is excluded. The low-energy properties of ${\mathrm{Tm}}_3{\mathrm{SbO}}_7$ are dominated by the lowest non-Kramers quasidoublet of ${\mathrm{Tm}}_1^{3+}$, and the energy splitting is regarded as an intrinsic transverse field. Therefore, the low-temperature paramagnetic phenomenon in ${\mathrm{Tm}}_3{\mathrm{SbO}}_7$ is explained by a transverse field Ising model, which is supported by the quantitative simulation of specific heat data. In addition, the perturbation from ${\mathrm{Tm}}_2^{3+}$ may play an important role in accounting for the low temperature spin dynamics behavior observed by $\mu \mathrm{SR}$.

• Received 24 January 2022
• Revised 27 March 2022
• Accepted 3 May 2022

DOI:https://doi.org/10.1103/PhysRevB.105.174418