Ferrimagnetism and half-metallicity in Cr-substituted Mn_4-CrAl₁₁

Area of Science:

• Materials Science
• Solid State Physics
• Inorganic Chemistry

Background:

• The Mn-Cr-Al system is explored for novel magnetic properties.
• Understanding the structural and magnetic behavior of disordered alloys is crucial.

Purpose of the Study:

• Synthesize single crystals of disordered Mn-Cr-Al.
• Characterize their structural, magnetic, and electronic properties.
• Investigate the potential for half-metallicity.

Main Methods:

• Flux method for single crystal synthesis.
• Energy-dispersive X-ray spectroscopy (EDS) for elemental analysis.
• X-ray diffraction (XRD) for structural determination.
• Magnetic measurements (SQUID magnetometry).
• Density functional theory (DFT) calculations.

Main Results:

• Single crystals of disordered Mn_4-xCr_xAl₁₁ were successfully synthesized.
• X-ray diffraction confirmed crystallization in space group P1¯, isostructural with Mn₄Al₁₁ and Cr₄Al₁₁.
• Magnetic measurements revealed ferrimagnetic behavior with a low effective moment (μ_eff≈1.012±0.004μ_B/f.u.) and a high transition temperature.
• DFT calculations indicated the opening of a bandgap in the spin-up channel near the Fermi level with increasing Cr content, suggesting half-metallicity.

Conclusions:

• Disordered Mn-Cr-Al alloys exhibit promising ferrimagnetic properties.
• The observed structural and magnetic characteristics are consistent with related intermetallic compounds.
• The potential for half-metallicity, indicated by DFT, warrants further investigation for spintronic applications.