Magnetic memory devices
Embodiments of the inventive concepts provide magnetic memory devices. The magnetic memory device includes a magnetic tunnel junction including a free layer, a pinned layer, and a tunnel barrier layer between the free layer and the pinned layer. The free layer includes a perpendicular magnetic material doped with non-magnetic impurities.
1. A magnetic memory device comprising:
a magnetic tunnel junction comprising a free layer, a pinned layer, and a tunnel barrier layer between the free layer and the pinned layer,
wherein the free layer includes a perpendicular magnetic material doped with non-magnetic impurities,
wherein the non-magnetic impurities include a transition metal or a rare-earth element,
wherein the perpendicular magnetic material has a crystal lattice, and
wherein the transition metal of the non-magnetic impurities or the rare-earth element of the non-magnetic impurities is located at interstitial sites of the crystal lattice of the perpendicular magnetic material.
2. The magnetic memory device of claim 1 ,
wherein the non-magnetic impurities have an atomic number equal to or greater than 30 and smaller than 60.
3. The magnetic memory device of claim 2 ,
wherein a concentration of the non-magnetic impurities included in the free layer ranges from 1 at % to 10 at %.
4. The magnetic memory device of claim 1 ,
wherein the non-magnetic impurities have an atomic number equal to or greater than 60.
5. The magnetic memory device of claim 4 ,
wherein a concentration of the non-magnetic impurities included in the free layer ranges from 1 at % to 5 at %.
6. The magnetic memory device of claim 1 ,
wherein the non-magnetic impurities have a spin-orbit coupling constant equal to or greater than 250 cm −1 and smaller than 1000 cm −1 .
7. The magnetic memory device of claim 6 ,
wherein a concentration of the non-magnetic impurities included in the free layer ranges from 1 at % to 10 at %.
8. The magnetic memory device of claim 1 ,
wherein the non-magnetic impurities have a spin-orbit coupling constant equal to or greater than 1000 cm −1 .
9. The magnetic memory device of claim 8 ,
wherein a concentration of the non-magnetic impurities included in the free layer ranges from 1 at % to 5 at %.
10. The magnetic memory device of claim 1 ,
wherein the free layer has a magnetization direction tilted at an acute angle from a direction perpendicular to a top surface of the free layer.
11. The magnetic memory device of claim 10 ,
wherein the acute angle increases as a concentration of the non-magnetic impurities increases.
12. The magnetic memory device of claim 1 ,
wherein the free layer includes a plurality of magnetic domains, and
wherein each of the magnetic domains has a magnetization direction tilted at an acute angle from a direction perpendicular to a top surface of the free layer.
13. The magnetic memory device of claim 1 ,
wherein the pinned layer has a magnetization direction perpendicular to a top surface of the free layer.
14. The magnetic memory device of claim 1 ,
wherein spin-orbit interaction occurs between the perpendicular magnetic material and the non-magnetic impurities.
15. The magnetic memory device of claim 14 ,
wherein the spin-orbit interaction is Dzyaloshinskii-Moriya interaction.
16. A magnetic memory device comprising:
a magnetic tunnel junction comprising a free layer, a pinned layer, and a tunnel barrier layer between the free layer and the pinned layer,
wherein the free layer has a magnetization direction tilted at an acute angle from a direction perpendicular to a top surface of the free layer,
wherein the pinned layer has a magnetization direction perpendicular to the top surface of the free layer,
wherein the free layer is a perpendicular magnetic material doped with non-magnetic impurities,
wherein the non-magnetic impurities include a transition metal or a rare-earth element,
wherein the perpendicular magnetic material has a crystal lattice, and
wherein the transition metal of the non-magnetic impurities or the rare-earth element of the non-magnetic impurities is located at interstitial sites of the crystal lattice of the perpendicular magnetic material.
17. The magnetic memory device of claim 16 ,
wherein the free layer includes a perpendicular magnetic material doped with non-magnetic impurities, and
wherein the acute angle increases as a concentration of the non-magnetic impurities increases.
18. The magnetic memory device of claim 16 ,
wherein the free layer includes a plurality of magnetic domains, and
wherein each of the magnetic domains has a magnetization direction tilted at an acute angle from the direction perpendicular to the top surface of the free layer.