We systematically investigate $g$-factor anisotropy in two-dimensional van der Waals magnets $\mathrm{Cr}{X}_3$ $(X=\mathrm{Cl}, \mathrm{Br}, \mathrm{I})$ using broadband magnetic resonance for magnetic ordered states below the critical temperature $\left(T_{\text{cr}}\right)$ and for paramagnetic states above $T_{\text{cr}}$, with varied field orientations. Despite sharing the same layered honeycomb lattice, these compounds exhibit contrasting anisotropies: ${\mathrm{CrCl}}_3$ is an easy-plane antiferromagnet, whereas ${\mathrm{CrBr}}_3$ and ${\mathrm{CrI}}_3$ are easy-axis ferromagnets. From temperature-dependent resonance dispersions with fields applied parallel and perpendicular to the $\mathit{c}$ axis, we uncover opposite trends of $g$-factor anisotropy: $g_{\mathrm{c}}>g_{\mathrm{ab}}$ in ${\mathrm{CrBr}}_3$ and ${\mathrm{CrI}}_3$, but $g_{\mathrm{c}}<g_{\mathrm{ab}}$ in ${\mathrm{CrCl}}_3$. Across the $\mathrm{Cr}{X}_3$ family, both the sign and the magnitude of the $g$ shift are found to correlate closely with the effective anisotropy field, suggesting that magnetic anisotropy provides a useful handle for tuning spin dynamics in van der Waals magnets.

Close

PrevNext

View figure in article

• Antiferromagnetism
• Spin dynamics
• 2-dimensional systems
• Ferromagnetic resonance