In magnetically frustrated systems, competing exchange interactions suppress long-range magnetic order and give rise to nontrivial ground states. In this study, we investigate the magnetic semiconductor ${\text{YbCuS}}_2$, which crystallizes in the orthorhombic $Pnma$ structure. In this structure, the Yb ions form an effective spin-1/2 zigzag chain along the $b$ axis. ${\text{YbCuS}}_2$ exhibits the first-order phase transition at $T_{\mathrm{O}}$ $=$ 0.95 K, accompanied by an incommensurate modulation along the $b$ axis with reduced Yb moments. We synthesize twinned crystals composed of three domains that share the $c$ axis through nearly 120-degree rotations, to conduct specific heat and magnetization measurements. Below $T_{\mathrm{O}}$, we observe an increase in magnetization between 3 and 7 T only for $B$ $\perp$ $c$, reminiscent of a magnetization plateau, while no such feature is observed for $B\parallel c$. We attribute this anisotropic behavior to on-site anisotropy arising from the crystalline electric field of the Yb ion. Accordingly, the 1/3 magnetization plateau must manifest itself for the magnetic fields applied along the $a$ axis, which is consistent with the anisotropic magnetic-field and temperature phase diagrams for $B$ $\perp$ $c$ and $B\parallel c$.

Close

PrevNext

View figure in article

• Magnetic anisotropy
• Magnetic order
• Magnetism
• 1-dimensional spin chains
• Chalcogens
• Lanthanides
• Magnetic semiconductors
• Magnetization measurements
• Specific heat measurements