Hostname: page-component-7479d7b7d-qs9v7 Total loading time: 0 Render date: 2024-07-12T02:22:21.708Z Has data issue: false hasContentIssue false
  • English
  • Français

Multilevel Magnetoresistance in a Structure Consisting of two spin-valves

Published online by Cambridge University Press:  21 March 2011

Kebin Li ,
Yihong Wu ,
Jinjun Qiu ,
Guchang Han ,
Zaibing Guo  and
Towchong Chong
Kebin Li
Affiliation:
Department of Electrical and Computer Engineering, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260
Yihong Wu
Affiliation:
Department of Electrical and Computer Engineering, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260
Jinjun Qiu
Affiliation:
Department of Electrical and Computer Engineering, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260
Guchang Han
Affiliation:
Department of Electrical and Computer Engineering, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260
Zaibing Guo
Affiliation:
Department of Electrical and Computer Engineering, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260
Towchong Chong
Affiliation:
Data Storage Institute, DSI Building, 5 Engineering Drive 1, Singapore 117608
Get access

Abstract

The magnetic and electrical properties as well as the structural characteristics have been studied on a series of samples with structure substrate (Sub)/SV(1)/Al2O35nm/SV(2). Here, SV(1) is either CoFe/IrMn based spin-valve (SV) such as Ta5/NiFe2/IrMn8/CoFe2/Cu2.6/CoFe2/Ta5 (thicknesses are in nanometers) bottom SV or Ta5/NiFe2/CoFe1.5/Cu2.6/CoFe2/FeMn10/Ta5 top SV and SV(2) is Ta5/NiFe2/CoFe1.5(or 2)/Cu2.6/CoFe2/IrMn8/Ta5 top SV. SV(1) and SV(2) in the structure are decoupled by a Al2O3 layer with 5nm in the magnetic properties, however, they are in parallel connection in the electrical properties. In a sample with structure Sub/Ta5/NiFe2/IrMn8/CoFe2/Cu2.6/CoFe2/Ta5/Al2O35/Ta5/NiFe2/CoFe2/Cu2.6/CoFe2/IrMn8/Ta5, five magnetoresistance states which are related to five magnetization states have been observed after the sample was annealed at T=220 °C with a field strength of 1T under high vacuum because of different interlayer coupling fields (Hint) in the top and bottom CoFe/IrMn based SVs (Hint is about 12.21 Oe in the top CoFe/IrMn SV and 29.3 Oe in the bottom CoFe/IrMn based SV). In a sample with structure Sub/Ta5/NiFe2/CoFe1.5/Cu2.6/CoFe2/FeMn10/Ta5/Al2O35/Ta5/NiFe2/CoFe1.5/Cu2.6/CoFe2 /IrMn8/Ta5, since the blocking temperature of the CoFe/FeMn based SV (Tb is about 150 °C) is lower than that of CoFe/IrMn based SV (Tb is about 230 °C), the spins can be easily engineered and therefore various magnetoresistance states can be obtained when the sample is magnetically annealed at different temperatures in a proper annealing sequence. By properly selecting materials and controlling the magnetically annealing conditions, multilevel giant magnetoresistance (MR) magnetic random access memory (MRAM) cell can be realized, which will significantly improve the MRAM data storage density without increasing any additional processing complexity.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 674: Symposia T/U/V – Applications of Ferromagnetic and Optical Materials, Storage and Magnetoelectronics , 2001 , T3.1
Copyright
Copyright © Materials Research Society 2001

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

[1] Jeong, Won-Cheol, Lee, Byung-II, and Joo, Seung-Ki, J. Appl. Phys. 85, 4782(1999)Google Scholar
[2] Moon, K.-S., Fontana, R.E. Jr, and Parkin, S. S. P., Appl. Phys. Lett. 74, 3690 (1999)10.1063/1.123222Google Scholar
[3] Fuke, Hiromi Niu, Saito, Kazuhiro, Kamiguchi, Yuzo, Iwasaki, Hitoshi, and Sahashi, Masashi, J. Appl. Phys. 81, 4004(1997)10.1063/1.364920Google Scholar
[4] Anderson, Geoff, Huai, Yiming, and Miloslawsky, Lena, J. Appl. Phys. 87, 6989(2000)10.1063/1.372907Google Scholar
[5] Devasahayam, A. J., Sides, P. J., and Kryder, M.H., J. Appl. Phys. 83, 7216(1998)Google Scholar
[6] Cheng, S. -F. and Lubitz, P., J. Appl. Phys. 87, 4927(2000)10.1063/1.373205Google Scholar
[7] Fuke, Hiromi N., Saito, Kazuhiro, Yoshikawa, Masatoshi, Iwasaki, Hitoshi, and Sahashi, Masashi, Appl. Phys. Lett. 75, 3680(1999)Google Scholar
[8] Choe, G. and Gupta, S., Appl.Phys.Lett. 70, 1766(1997)10.1063/1.118650Google Scholar