Interface Tailoring Effect for Heusler Based CPP-GMR with an L1₂-Type Ag₃Mg Spacer

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Current perpendicular-to-plane (CPP) giant magnetoresistance (GMR) effects are crucial for magnetic sensor applications like hard disk drive read-heads.
• Improving the performance of these junctions is essential for advancing data storage technology.

Purpose of the Study:

• To investigate interface tailoring effects on Co₂Fe₀.₄Mn₀.₆Si (CFMS) based CPP-GMR junctions using an Ag₃Mg ordered alloy spacer.
• To evaluate the impact of ultra-thin Fe or Mg inserts on CPP-GMR performance and bias current density dependence.

Main Methods:

• Fabrication of CPP-GMR junctions incorporating CFMS and an Ag₃Mg spacer.
• Introduction of ultra-thin Fe or Mg inserts at the CFMS/Ag₃Mg interfaces.
• Evaluation of magnetoresistance (MR) ratio and output voltage at varying bias current densities (J).
• Determination of critical current density (Jc) from MR curves as a function of J.

Main Results:

• The MR ratio decreased with increasing insert thickness at low bias current densities.
• Device output showed weak dependence on insert thickness at high bias current densities, yielding ~4 mV output.
• Critical current density (Jc) increased with insert thicknesses up to 0.45 nm.

Conclusions:

• Interface engineering with Fe or Mg inserts enhances Jc in CFMS-based CPP-GMR junctions.
• The observed enhancement in Jc suggests a potential reduction in spin-transfer-torque effects.
• This reduction offers advantages for device applications by enabling lower noise levels.