Ferromagnetic Order of Reduced Magnetic Moments in a Frustrated Sawtooth Chain of the Magnetic Semiconductor ZnYb${}_2$S${}_4$

Abstract

In a sawtooth spin chain, competing nearest- and next-nearest-neighbor interactions suppress long-range order, yielding novel quantum states such as a spin-dimer singlet, 1/2 magnetization plateau, and spin contraction. Here, we investigate the magnetic properties of the orthorhombic semiconductor ZnYb${}_2$S${}_4$, in which Yb${}^{3+}$ ions with an effective spin-1/2 form a sawtooth chain along the $b$-axis. The specific heat exhibits a sharp peak at $T_{\mathrm{m}}$ $=$ 1.4 K, at which the magnetic entropy $S_{\mathrm{m}}$ reaches only 27% of $R$ln2. This reduced $S_{\mathrm{m}}$ at $T_{\mathrm{m}}$ indicates the entropy release of the ground state doublet of Yb${}^{3+}$ even for $T$ $>$ $T_{\mathrm{m}}$. The isothermal magnetization $M(B)$ at 0.28 K exhibits hysteresis for $\left|B\right|\le 0.2$ T and increases monotonically for $B>0.2$ T. The spontaneous magnetization is only 0.1 ${\mu }_{\mathrm{B}}$$/$Yb, an order of magnitude smaller than that expected for the ground state doublet of Yb${}^{3+}$. Moreover, in powder neutron diffraction measurements, no superlattice reflections due to antiferromagnetic order are observed for $T$ $<$ $T_{\mathrm{m}}$. Therefore, in the ground state, the Yb moments are ferromagnetically aligned, but their amplitude is reduced by magnetic frustration in the sawtooth Yb chain.

6 pages, 6 figures

References in corpus (13)

• $\mu$SR evidence for the U(1) quantum spin liquid ground state in the triangular antiferromagnet YbMgGaO${}_4$
• Anisotropic field-induced ordering in the triangular-lattice quantum spin liquid NaYbSe${}_2$
• Observation of Magnetic Monopoles in Spin Ice
• Field-induced instability of the quantum-spin-liquid ground state in the $J_{\mathrm{eff}}=\frac{1}{2}$ triangular-lattice compound NaYbO${}_2$
• Field-induced magnetic transition and spin fluctuation in quantum spin liquid candidate CsYbSe${}_2$
• The sawtooth chain: From Heisenberg spins to Hubbard electrons
• Enhancement of magnetization plateaus in low dimensional spin systems
• Analytical and numerical studies of the one-dimensional sawtooth chain
• Electric field driven flat bands: Enhanced magnetoelectric and electrocaloric effects in frustrated quantum magnets
• Exact matrix product states at the quantum Lifshitz tricritical point in a spin-1/2 zigzag-chain antiferromagnet with anisotropic $\Gamma$-term
• Phase diagram of the quantum spin-1/2 Heisenberg-$\Gamma$ model on a frustrated zigzag chain
• Deriving quantum spin model for a zigzag-chain ytterbium magnet with anisotropic exchange interactions
• Noncollinear phase of the antiferromagnetic sawtooth chain

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