Synthesis of Hexagonal FeMnP Thin Films from a Single-Source Molecular Precursor

Area of Science:

• Materials Science
• Inorganic Chemistry
• Thin Film Deposition

Background:

• Heterobimetallic phosphides are advanced materials with unique electronic and magnetic properties.
• Synthesizing ternary phosphides with controlled stoichiometry and phase is challenging.
• Previous methods for FeMnP required high temperatures, limiting applications.

Purpose of the Study:

• To synthesize the first heterobimetallic phosphide thin film containing iron, manganese, and phosphorus.
• To develop a low-temperature synthesis route for the metastable hexagonal FeMnP phase.
• To characterize the structural and magnetic properties of the synthesized thin film.

Main Methods:

• Single-source precursor (FeMn(CO)₈ (μ-PH₂ )) utilization.
• Home-built metal-organic chemical vapor deposition (MOCVD) apparatus.
• Substrate screening (quartz vs. alumina) for optimal film homogeneity.
• Powder X-ray diffraction (PXRD) and selected area electron diffraction (SAED) for phase identification.
• Magnetic susceptibility measurements to determine effective magnetic moment.

Main Results:

• Successful synthesis of a heterobimetallic FeMnP thin film from a single precursor.
• Identification of a metastable, hexagonal FeMnP phase at low temperatures, previously only observed above 1200°C.
• Alumina substrate yielded a more homogeneous film compared to quartz.
• Measured effective moment (3.68 μ_B) aligns with theoretical values for the hexagonal phase, distinct from the antiferromagnetic orthorhombic phase.

Conclusions:

• Demonstrated a novel single-source precursor MOCVD approach for ternary phosphide thin films.
• Achieved low-temperature synthesis of the metastable hexagonal FeMnP phase.
• Highlighted the potential of this method for accessing unique material phases and properties.