Structural, thermodynamic, and local probe investigations of a honeycomb material Ag${}_3$LiMn${}_2$O${}_6$

Abstract

The system Ag[Li${}_{1/3}$Mn${}_{2/3}$]O${}_2$ belongs to a quaternary 3R-delafossite family and crystallizes in a monoclinic symmetry with space group $C2/m$ and the magnetic Mn${}^{4+}$($S=3/2$) ions form a honeycomb network in the $ab$-plane. An anomaly around 50 K and the presence of antiferromagnetic (AFM) coupling (Curie-Weiss temperature ${\theta }_{CW}\sim -51$ K) were inferred from our magnetic susceptibility data. The magnetic specific heat clearly manifests the onset of magnetic ordering in the vicinity of 48\,K and the recovered magnetic entropy, above the ordering temperature, falls short of the expected value, implying the presence of short-range magnetic correlations. The (ESR) line broadening on approaching the ordering temperature $T_{\mathrm{N}}$ could be described in terms of a Berezinski-Kosterlitz-Thouless (BKT) scenario with $T_{\mathrm{KT}}=40(1)$ K. ${}^7$Li NMR line-shift probed as a function of temperature tracks the static susceptibility (K${}_{iso}$) of magnetically coupled Mn${}^{4+}$ ions. The ${}^7$Li spin-lattice relaxation rate (1/$T$${}_1$) exhibits a sharp decrease below about 50 K. Combining our bulk and local probe measurements, we establish the presence of an ordered ground state for the honeycomb system Ag${}_3$LiMn${}_2$O${}_6$.Our ab-initio electronic structure calculations suggest that in the $ab$-plane, the nearest neighbor (NN) exchange interaction is strong and AFM, while the next NN and the third NN exchange interactions are FM and AFM respectively. In the absence of any frustration the system is expected to exhibit long-range, AFM order, in agreement with experiment.

11 pages, 13 figures, accepted in Phys Rev B

References in corpus (6)

• Kitaev Materials
• On the strong impact of doping in the triangular antiferromagnet CuCrO2
• Detection of XY behaviour in weakly anisotropic quantum antiferromagnets on the square lattice
• Effective magnetic interactions in spin-orbit coupled $d^4$ Mott insulators
• Charge disproportionation and collinear magnetic order in the frustrated triangular antiferromagnet AgNiO2
• Unconventional magnetism in the 4d${}^4$ based ($S=1$) honeycomb system Ag${}_3$LiRu${}_2$O${}_6$

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• Survival of magnetic correlations above ordering temperature in a ferromagnetically ordered classical kagomé magnet: Li9Cr3(P2O7)3(PO4)2
• Novel Quantum Spin Liquid States in the $S=\frac{1}{2}$ Three-Dimensional Compound Y${}_3$Cu${}_2$Sb${}_3$O${}_{14}$
• Spin-qubit Noise Spectroscopy of Magnetic Berezinskii-Kosterlitz-Thouless Physics
• Interplay of phonons, intertwined density waves, and induced spin density wave in trilayer nickelates Pr4-xLaxNi3O10