Double phase transition in the triangular antiferromagnet Ba${}_3$CoTa${}_2$O${}_9$

Abstract

Here, we report the synthesis and magnetic properties of a new triangular lattice antiferromagnet Ba${}_3$CoTa${}_2$O${}_9$. The effective spin of Co${}^{2+}$ is found to be $J=1/2$ at low temperatures due to the combined effect of crystal field and spin-orbit coupling. Ba${}_3$CoTa${}_2$O${}_9$ undergoes two successive magnetic phase transitions at $T_{N1}\simeq 0.70$~K and $T_{N2}\simeq 0.57$~K in zero applied field, which is typical for triangular antiferromagnets with the easy-axis magnetic anisotropy. With increasing field, the transition anomalies are found to shift toward low temperatures, confirming the antiferromagnetic nature of the transitions. At higher fields, the transition peaks in the heat capacity data disappear and give way to a broad maximum, which can be ascribed to a Schottky anomaly due to the Zeeman splitting of spin levels. The $H-T$ phase diagram of the compound shows three distinct phases. The possible nature of these phases is discussed.

6 pages, 7 figures

References in corpus (3)

• Magnetic properties of BaCdVO(PO_4)_2: a strongly frustrated spin-1/2 square lattice close to the quantum critical regime
• Quantum stabilization of 1/3-magnetization plateau in Cs_2CuBr_4
• Magnetic Phase Diagram of the S=1/2 Triangular-Lattice Heisenberg Antiferromagnet Ba3CoNb2O9

Cited by in corpus (5)

• Anisotropic field-induced ordering in the triangular-lattice quantum spin liquid NaYbSe${}_2$
• Field-induced instability of the quantum-spin-liquid ground state in the $J_{\mathrm{eff}}=\frac{1}{2}$ triangular-lattice compound NaYbO${}_2$
• Six-loop $\epsilon$ expansion study of three-dimensional $O(n)\times O(m)$ spin models
• Double magnetic transitions and exotic field induced phase in the triangular lattice antiferromagnets Sr${}_3$Co(Nb,Ta)${}_2$O${}_9$
• Magnetic phase diagram in three-dimensional triangular-lattice antiferromagnet Sr${}_3$CoTa${}_2$O${}_9$ with small easy-axis anisotropy