Experimental Realization of a Unique Class of Compounds: XY-Antiferromagnetic Triangular Lattices, KAg₂Fe[VO₄]₂ and RbAg₂Fe[VO₄]₂, with Ferroelectric Ground States

Abstract

AAg 2 Fe [VO 4 ] 2 with A = K or Rb was synthesized by solid state methods and characterized by thermodynamic properties measurements (Neél order at T N ≈ 3.0 K). The respective nuclear (a K,Rb = 5.48 Å, c K = 7.212 Å, c Rb = 7.357 Å, P3̅ , Z = 1) and magnetic structures were refined using neutron diffraction in applied magnetic fields. The results indicate enhanced structural stability of the P3̅ structure and the realization of a frustrated triangular lattice with antiferromagnetic XY-anisotropies. Two magnetic structures were identified: a helical and chiral Y-phase with a propagation vector of (1/3, 1/3, ≈ 0.39) and a commensurate up−up−down phase. These unique compounds offer convenient experimental access for optimizing the features and properties of ferroaxial multiferroic materials.

Unconventional spin excitations in the S=32 triangular antiferromagnet RbAg2Cr[VOLee1, Klauer2, Menten3 et al. 2020Phys. Rev. B8060View full textAdd to dashboardCite

“…It is theoretically well established that antiferromagnetic Heisenberg spin systems on the undistorted triangular lattice exhibit a chiral 120 • long-range magnetic order regardless of the spin magnitude [3][4][5][6]. The TL compounds AAg 2 Fe[VO 4 ] 2 (A = K or Rb) [7] and RbFe[MoO 4 ] 2 [8] with S = 5/2 show this ground state, as predicted. In contrast, κ-(BEDT-TTF) 2 Cu 2 (CN) 3 , EtMe 3 Sb[Pd(dmit) 2 ] 2 , and YbMgGaO 4 with S = 1/2 have been classified as QSL materials [9][10][11].…”

Hydrothermal synthesis of single crystals of transition metal vanadates in the glaserite phase

“…[17] Appropriately it is named after Christopher Glaser, perhaps the first practicing descriptive inorganic chemist. [18] It has an enormous range of derivatives, [19] whereby the potassium site can range from alkali to alkaline earth ions, [20] the sodium site can be occupied by metals ranging from transition metals [21] to rare earths in a variety of oxidation states, [22] and the tetrahedral building block can be virtually any known tetrahedron including phosphates, vanadates, [14,23,24] chromates, [17] ruthenates [25] and silicates. [26] As such the phase behaves as a highly adaptive solid-state structure.…”

Synthesis and characterization of new fluoride-containing manganese vanadates A2Mn2V2O7F2 (A=Rb, Cs) and Mn2VO4F

“…The vanadates differ somewhat in that they are measurably larger and most importantly, they introduce d-orbitals into the bridging ligand. [9][10][11][12][13][14][15] This has the potential to change the coupling behavior between the open shell metal ions and reverse the Goodenough-Kanamori-Anderson superexchange rules. [16,17] Thus the fuller development of the metal vanadates is clearly warranted.…”