ASb₃Mn₉O₁₉ (A = K or Rb): New Mn-Based 2D Magnetoplumbites with Geometric and Magnetic Frustration.

Area of Science:

• Solid State Chemistry
• Magnetism
• Materials Science

Background:

• Magnetoplumbites are hexagonal ferrites known for high magnetic ordering temperatures, suitable for permanent magnets.
• Magnetic frustration is seldom observed in magnetoplumbite structures.

Purpose of the Study:

• To report the discovery and characterization of the first manganese-based magnetoplumbite.
• To investigate novel magnetoplumbites incorporating pnictogens (Sb), specifically ASb3Mn9O19 (A = K or Rb).
• To explore the magnetic properties and structural characteristics, particularly focusing on magnetic frustration.

Main Methods:

• Synthesis and characterization of new magnetoplumbite compounds.
• DC magnetic susceptibility measurements.
• X-ray photoelectron spectroscopy (XPS).
• Neutron powder diffraction (NPD) at low temperatures.
• Heat capacity measurements.
• Reverse Monte Carlo (RMC) refinements.

Main Results:

• The synthesis of the first Mn-based magnetoplumbite, ASb3Mn9O19 (A = K, Rb), was successful.
• Mn3+ cations form three geometrically frustrated sublattices: Kagome, triangular, and puckered honeycomb.
• Strong antiferromagnetic spin-spin coupling and low-temperature magnetic features were observed.
• No long-range magnetic ordering was detected in KSb3Mn9O19 down to 3 K.
• RbSb3Mn9O19 exhibited an incommensurate magnetic structure at 3 K.
• Diffuse scattering in NPD patterns indicated short-range spin ordering and 2D magnetic correlations due to frustrated magnetism.

Conclusions:

• The new Mn-based magnetoplumbites with Sb demonstrate geometrically frustrated magnetism, a rare phenomenon in this material family.
• These compounds exhibit complex magnetic behaviors, including short-range ordering and 2D correlations, driven by frustrated sublattices.
• The findings expand the scope of magnetoplumbite research and offer insights into frustrated magnetic systems.