Magnetic tunnel junction element and memory device including magnetic tunnel junction element

A magnetic tunnel junction element, comprising:

• a pinned layer and a free layer facing each other;
• a buffer layer on the pinned layer;
• a polarization enhancement layer between the buffer layer and the free layer;
• and
• a tunnel barrier layer between the polarization enhancement layer and the free layer,
• wherein the buffer layer is amorphous and includes CoFeBX, and X is W, Mo, Re or Ta,
• the polarization enhancement layer comprises a first polarization enhancement layer and a second polarization enhancement layer,
• the second polarization enhancement layer is between the first polarization enhancement layer and the free layer, and
• a boron concentration included in the second polarization enhancement layer is lower than a boron concentration included in the first polarization enhancement layer.

A memory device, comprising:

• a plurality of memory cells each including a magnetic tunnel junction element and a switching element connected to the magnetic tunnel junction element,
• wherein the magnetic tunnel junction element comprises:
• a pinned layer and a free layer facing each other;
• a buffer layer on the pinned layer;
• an auxiliary layer on the buffer layer;
• a polarization enhancement layer between the auxiliary layer and the free layer;
• and
• a tunnel barrier layer between the polarization enhancement layer and the free layer,
• wherein the buffer layer is amorphous and includes CoFeBX, and X is W, Mo, Re or Ta,
• the auxiliary layer includes W, Mo, or Ta.