A group-IV ferromagnetic semiconductor: MnxGe1-x.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Semiconductor Spintronics

Background:

• Group-IV semiconductors are crucial for microelectronics.
• Developing ferromagnetic semiconductors is key for spintronic applications.
• Controlling magnetic properties via electrical gating is highly desirable.

Purpose of the Study:

• To investigate the epitaxial growth of manganese-doped germanium (Mn(x)Ge(1-x)) as a group-IV ferromagnetic semiconductor.
• To explore the relationship between manganese concentration and Curie temperature.
• To demonstrate electrical control over the ferromagnetic properties of Mn(x)Ge(1-x).

Main Methods:

• Epitaxial growth of Mn(x)Ge(1-x) thin films.
• Temperature-dependent magnetization measurements to determine Curie temperature.
• Electrical gating experiments to modulate ferromagnetic order.
• Density-functional theory (DFT) calculations for theoretical analysis.

Main Results:

• Curie temperature increases linearly with manganese concentration (25–116 K).
• Ferromagnetic order is controllable using a +/-0.5 V gate voltage due to p-type semiconducting character and hole-mediated exchange.
• DFT calculations reveal dominant long-range ferromagnetic interactions over short-range antiferromagnetic interactions.
• Theoretical predictions of transition temperatures exceed experimental values, attributed to suppressed magnetic Mn atoms and hole concentration.

Conclusions:

• Mn(x)Ge(1-x) is a promising group-IV ferromagnetic semiconductor with electrically tunable properties.
• The observed phenomena are consistent with theoretical predictions and material limitations.
• This material holds potential for integration into microelectronic and spintronic devices.