Magnetic Properties Controlled by Interstitial or Interlayer Cations in Iron Chalcogenides.

Area of Science:

• Solid State Physics
• Materials Science
• Computational Chemistry

Background:

• Iron chalcogenides are promising materials for electronic applications.
• Understanding their magnetic properties is crucial for technological advancement.
• Previous studies have focused on iron pnictides, leaving chalcogenides less explored.

Purpose of the Study:

• To investigate the factors controlling magnetic order in iron chalcogenides.
• To explore the role of interstitial and interlayer cations in magnetic phase transitions.
• To understand the magnetic instability relevant to superconductivity in these materials.

Main Methods:

• Density functional theory (DFT) calculations were employed.
• Systematic variation of interstitial iron concentration and position in Fe1+yTe.
• Analysis of magnetic instability at the (π, π) wavevector in KyFe2Se2.

Main Results:

• Magnetic order in Fe1+yTe is dictated by interstitial iron height and concentration, leading to diverse magnetic states.
• Magnetic instability at (π, π) in KyFe2Se2 is significantly enhanced with low y values.
• Itinerant electrons play a significant role in iron chalcogenides, similar to iron pnictides.

Conclusions:

• Interstitial and interlayer cations are key determinants of magnetic properties in iron chalcogenides.
• The findings provide insights into the mechanisms behind magnetic phase transitions and instabilities.
• This research contributes to the understanding of electron correlations in iron-based materials.