Magnetic ground state of the Ising-like antiferromagnet DyScO3

We report on the low-temperature magnetic properties of the ${\mathrm{DyScO}}_3$ perovskite, which were characterized by means of single crystal and powder neutron scattering, and by magnetization measurements. Below $T_N=3.15$ K, ${\mathrm{Dy}}^{3+}$ moments form an antiferromagnetic structure with an easy axis of magnetization lying in the $ab$ plane. The magnetic moments are inclined at an angle of $\sim \pm {28}^{\circ }$ to the $b$ axis. We show that the ground-state Kramers doublet of ${\mathrm{Dy}}^{3+}$ is made up of primarily $|\pm 15/2⟩$ eigenvectors and well separated by a crystal field from the first excited state at $E_1=24.9$ meV. This leads to an extreme Ising single-ion anisotropy, $M_{\perp }/M_{\parallel }\sim 0.05$. The transverse magnetic fluctuations, which are proportional to $M_{\perp }^2/M_{\parallel }^2$, are suppressed, and only moment fluctuations along the local Ising direction are allowed. We also found that the Dy-Dy dipolar interactions along the crystallographic $c$ axis are two to four times larger than in-plane interactions.