Electronic Modulation in Site-Selective Occupation of Quasi-2D Triangular-Lattice Cs₂CuCl_4-Br Perovskite Probed by...

Area of Science:

• Materials Science
• Condensed Matter Physics
• Solid State Chemistry

Background:

• Two-dimensional (2D) all-inorganic perovskites are promising for integration into electronic and magnetic devices.
• Controllable electronic manipulation in frustrated magnetic systems is key for advanced applications.

Purpose of the Study:

• Investigate the electronic and magnetic properties of quasi-2D all-inorganic perovskites Cs2CuCl4-xBrx.
• Understand the influence of halogen content (chlorine and bromine) on material properties.

Main Methods:

• Element-specific synchrotron-radiation photoelectron techniques.
• X-ray absorption spectroscopy (XAS) at Cu L2,3 edges.
• X-ray magnetic circular dichroism (XMCD) spectroscopy.
• Density functional theory (DFT) calculations.

Main Results:

• Halogen content significantly influences electronic transitions at the Cu L2,3 edges, with chlorine's higher electronegativity playing a key role.
• Valence band edge position relative to the Fermi energy (EF) is affected by halogen composition.
• Antiferromagnetism was observed at room temperature in mixed and bromine-rich Cs2CuCl4-xBrx compounds.

Conclusions:

• Site-selective occupation and halogen content strongly modulate electronic and magnetic properties in Cs2CuCl4-xBrx perovskites.
• These findings support the potential for energy- and cost-efficient perovskite devices.
• The study highlights the tunability of these solution-based, low-temperature-growth materials for future applications.