Abstract
We investigated the influence of insulating barrier thickness and the Ti composition dependence of the band structure of Al-oxide on the resistance and tunneling magnetoresistance (TMR) behavior of the magnetic tunnel junction (MTJ). Low resistance × area (RA) value (1.1 MΩ μm 2) was achieved by decreasing the Al-oxide thickness down to 1.0 nm. However, this led to the partial oxidation of the bottom ferromagnetic (FM) electrode of the junction and non-continuous thin barriers by the occurrence of pinholes, with low TMR ratio of 8.3%. For an alternative for low RA value, we developed a new Ti-alloyed Al-oxide (TiAlO x) that had lower band gap than Al-oxide as an insulating barrier of MTJ. As the Ti concentration increased up to 5.33 at.% Ti in Al, the RA value of the MTJs was reduced from 9.5 to 0.69 MΩ μm 2, owing to the band-gap reduction of TiAlO x caused by the formation of extra bands, mainly composed of Ti-3d orbitals, within the band gap. It was analyzed that TiAlO x has localized d states in the band gap below the conduction band. In addition, the TMR ratio increased with the Ti concentration and reached a maximum of 49% at 5.33 at.% Ti owing to the microstructural evolution of Ti-Al alloy film in the pre-oxidation state.
| Original language | English |
|---|---|
| Pages (from-to) | 18-20 |
| Number of pages | 3 |
| Journal | Current Applied Physics |
| Volume | 7 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - 2007 Jan 1 |
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Keywords
- Barrier thickness
- Low resistance MTJ
- Magnetic tunnel junction
- TiAlO barrier
ASJC Scopus subject areas
- Condensed Matter Physics
- Surfaces and Interfaces
- Materials Science (miscellaneous)
Cite this
Influence of thickness and band structure of insulating barriers on resistance and tunneling magnetoresistance properties of magnetic tunnel junctions with Al-oxide and Ti-alloyed Al-oxide barriers. / Song, Jin Oh; Lee, Seong Rae; Shin, Hyun Joon.
In: Current Applied Physics, Vol. 7, No. 1, 01.01.2007, p. 18-20.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Influence of thickness and band structure of insulating barriers on resistance and tunneling magnetoresistance properties of magnetic tunnel junctions with Al-oxide and Ti-alloyed Al-oxide barriers
AU - Song, Jin Oh
AU - Lee, Seong Rae
AU - Shin, Hyun Joon
PY - 2007/1/1
Y1 - 2007/1/1
N2 - We investigated the influence of insulating barrier thickness and the Ti composition dependence of the band structure of Al-oxide on the resistance and tunneling magnetoresistance (TMR) behavior of the magnetic tunnel junction (MTJ). Low resistance × area (RA) value (1.1 MΩ μm 2) was achieved by decreasing the Al-oxide thickness down to 1.0 nm. However, this led to the partial oxidation of the bottom ferromagnetic (FM) electrode of the junction and non-continuous thin barriers by the occurrence of pinholes, with low TMR ratio of 8.3%. For an alternative for low RA value, we developed a new Ti-alloyed Al-oxide (TiAlO x) that had lower band gap than Al-oxide as an insulating barrier of MTJ. As the Ti concentration increased up to 5.33 at.% Ti in Al, the RA value of the MTJs was reduced from 9.5 to 0.69 MΩ μm 2, owing to the band-gap reduction of TiAlO x caused by the formation of extra bands, mainly composed of Ti-3d orbitals, within the band gap. It was analyzed that TiAlO x has localized d states in the band gap below the conduction band. In addition, the TMR ratio increased with the Ti concentration and reached a maximum of 49% at 5.33 at.% Ti owing to the microstructural evolution of Ti-Al alloy film in the pre-oxidation state.
AB - We investigated the influence of insulating barrier thickness and the Ti composition dependence of the band structure of Al-oxide on the resistance and tunneling magnetoresistance (TMR) behavior of the magnetic tunnel junction (MTJ). Low resistance × area (RA) value (1.1 MΩ μm 2) was achieved by decreasing the Al-oxide thickness down to 1.0 nm. However, this led to the partial oxidation of the bottom ferromagnetic (FM) electrode of the junction and non-continuous thin barriers by the occurrence of pinholes, with low TMR ratio of 8.3%. For an alternative for low RA value, we developed a new Ti-alloyed Al-oxide (TiAlO x) that had lower band gap than Al-oxide as an insulating barrier of MTJ. As the Ti concentration increased up to 5.33 at.% Ti in Al, the RA value of the MTJs was reduced from 9.5 to 0.69 MΩ μm 2, owing to the band-gap reduction of TiAlO x caused by the formation of extra bands, mainly composed of Ti-3d orbitals, within the band gap. It was analyzed that TiAlO x has localized d states in the band gap below the conduction band. In addition, the TMR ratio increased with the Ti concentration and reached a maximum of 49% at 5.33 at.% Ti owing to the microstructural evolution of Ti-Al alloy film in the pre-oxidation state.
KW - Barrier thickness
KW - Low resistance MTJ
KW - Magnetic tunnel junction
KW - TiAlO barrier
UR - http://www.scopus.com/inward/record.url?scp=33749265475&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=33749265475&partnerID=8YFLogxK
U2 - 10.1016/j.cap.2005.06.007
DO - 10.1016/j.cap.2005.06.007
M3 - Article
VL - 7
SP - 18
EP - 20
JO - Current Applied Physics
JF - Current Applied Physics
SN - 1567-1739
IS - 1
ER -