Thermal Characterization of Ultrathin MgO Tunnel Barriers

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Magnetic tunnel junctions (MTJs) with ultrathin MgO barriers are key components in magnetic random-access memory (MRAM).
• High programming currents in MRAM generate heat, potentially degrading MTJ performance and reliability.
• The tunnel magneto-Seebeck effect in MTJs opens possibilities for spin caloritronics.

Purpose of the Study:

• To thermally characterize ultrathin CoFeB/MgO multilayers with varying thicknesses.
• To determine the thermal conductivity of MgO tunnel barriers and understand thermal boundary resistance.
• To provide data for improved thermal analysis and design of MRAM devices.

Main Methods:

• Time-domain thermoreflectance (TDTR) measurements were employed for thermal characterization.
• Thermal modeling was used in conjunction with TDTR data.
• CoFeB/MgO multilayers with specific MgO thicknesses (1.0, 1.3, 1.6 nm) were fabricated and tested.

Main Results:

• The intrinsic thermal conductivity of annealed 1.0 nm MgO was found to be approximately 3.6 W m^-1 K^-1.
• The effective thermal conductivity of the MgO layer was determined to be approximately 0.85 W m^-1 K^-1.
• The study quantified the influence of thermal boundary resistance in ultrathin MgO layers.

Conclusions:

• The thermal properties of ultrathin MgO tunnel barriers have been elucidated.
• Accurate thermal characterization is essential for enhancing the reliability and endurance of MRAM devices.
• This research contributes to the precise thermal management strategies for next-generation memory technologies.