Abstract
Perpendicularly magnetized magnetic tunnel junction (p-MTJ) is a key element for developing high-density spin-transfer torque switching magnetoresistive random access memory. Recently, a large exchange coupling (IEC) in the synthetic antiferromagnetic reference layer with Ir interlayer was observed in p-MTJs. The evaluation of the IEC is, however, difficult due to the electrostatic breakdown of MTJs. This study demonstrates the evaluation of the IEC with Ir interlayer in giant magnetoresistive (GMR) nanopillar. We fabricated three kinds of perpendicularly magnetized GMR elements; bottom-free structures with Cu or Ir spacer, and top-free structure with Ir spacer. The magnetoresistance (RH) loops of all samples show sharp changes of the magnetoresistance at the magnetic fields over ±10 kOe, indicating the existence of the large IECs. In particular, a sharp change of the magnetoresistance at the field over ±20 kOe was found for the element with Cu of 2 nm thickness.
Highlights
Magnetized magnetic tunnel junctions (p-MTJs) with MgO-spacer is the core structure as memory cells in spin-transfer torque (STT) switching magnetoresistive random access memory (STT-MRAM).[1,2,3,4] For stable read/write operations in MgO-based Perpendicularly magnetized magnetic tunnel junction (p-MTJ),[5,6,7,8] the magnetization in the reference layer should be robust even under any situations subjected to perturbations such as external magnetic field and thermal fluctuation
For stable read/write operations in MgO-based p-MTJs,[5,6,7,8] the magnetization in the reference layer should be robust even under any situations subjected to perturbations such as external magnetic field and thermal fluctuation
The interlayer exchange coupling (IEC)[9,10,11,12,13,14,15] between two ferromagnets in the reference layer strongly fixes the direction of the magnetization in the p-SAF structure
Summary
Magnetized magnetic tunnel junctions (p-MTJs) with MgO-spacer is the core structure as memory cells in spin-transfer torque (STT) switching magnetoresistive random access memory (STT-MRAM).[1,2,3,4] For stable read/write operations in MgO-based p-MTJs,[5,6,7,8] the magnetization in the reference layer should be robust even under any situations subjected to perturbations such as external magnetic field and thermal fluctuation. The interlayer exchange coupling (IEC)[9,10,11,12,13,14,15] between two ferromagnets in the reference layer strongly fixes the direction of the magnetization in the p-SAF structure. All samples show sharp changes of the magnetoresistance at the magnetic fields larger than 10 kOe, indicating a large IEC in the reference layer with Ir spacer. The GMR element with Cu spacer of 2 nm thickness shows a magnetoresistance change at the field larger than 20 kOe
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