Double charge ordering states and spin ordering state observed in a RFe2O4 system

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Materials

Background:

• Layered quantum materials like RFe2O4 exhibit complex charge, spin, and lattice ordering.
• The precise nature and fine energy structure of the two-dimensional (2D) charge ordering (CO) state in these materials remain unclear.
• Previous experimental methods have not resolved the energy fine structure of the 2D CO state.

Purpose of the Study:

• To experimentally observe and characterize the fine energy structure of the 2D charge ordering (CO) state in RFe2O4.
• To investigate the relationship between charge ordering and spin ordering (SO) in this material system.
• To demonstrate the utility of Raman scattering for probing quantum orders in layered materials.

Main Methods:

• Utilized Raman scattering spectroscopy to probe the vibrational and electronic properties of polycrystalline Er0.1Yb0.9Fe2O4.
• Analyzed spectral data to identify distinct energy signatures associated with charge and spin ordering phenomena.
• Investigated the material at various temperatures to distinguish between different ordering states.

Main Results:

• Unambiguously observed double 2D charge ordering (CO) states at elevated temperatures.
• Quantified energy gaps for the double 2D CO states as 170 meV (41.2 THz) and 193 meV (46.6 THz).
• Identified a spin ordering (SO) state below 210 K with a characteristic energy of 45 meV (10.7 THz).

Conclusions:

• The study provides the first experimental observation of the fine energy structure of double 2D CO states in RFe2O4.
• New insights into the complex interplay of charge and spin orders in layered quantum materials were gained.
• Raman scattering is confirmed as a powerful optical technique for investigating quantum phenomena in layered materials.