Intrinsic Ferromagnetism in the Diluted Magnetic Semiconductor Co:TiO_{2}

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Diluted magnetic semiconductors (DIMS) are promising for spintronic applications.
• Understanding the factors influencing magnetism in oxide DIMS is critical for their development.

Purpose of the Study:

• To investigate the magnetic properties of Co:TiO2 anatase films.
• To determine the optimal growth conditions for intrinsic ferromagnetism.
• To elucidate the mechanism behind ferromagnetism in Co:TiO2.

Main Methods:

• Pulsed laser deposition (PLD) for film growth.
• Energy-dispersive spectrometry (EDS) and transmission electron microscopy (TEM) for microstructural analysis.
• Low-energy muon spin rotation (LE-μSR) for depth-resolved magnetic characterization.
• First principles calculations for theoretical insights.

Main Results:

• High deposition rates yielded homogeneous Co:TiO2 microstructures.
• Low oxygen partial pressure (≈10^-6 torr) and uniform structure resulted in fully magnetic films.
• Cobalt clustering was observed at very low deposition rates or post-annealing.
• First principles calculations confirmed carrier-mediated ferromagnetism induced by low oxygen partial pressure.

Conclusions:

• Co:TiO2 anatase films grown under specific conditions exhibit intrinsic ferromagnetism.
• Low oxygen partial pressure is key to achieving uniform, carrier-mediated ferromagnetism.
• Co:TiO2 is demonstrated to be an intrinsic diluted magnetic semiconductor.