자기터널절합에서 자기 및 자기저항의 접합크기 의존성

상카라나라얀; 호영강; 김철기; 김종오; 이의복; V.K. Sankaranarayanan; Yongkang Hu; CheolGi Kim; Chong-Oh Kim; Heebok Lee

Korean Journal of Materials Research, Vol.13, No.6, 369-373, June, 2003

DOI10.3740/MRSK.2003.13.6.369 Export Citation

자기터널절합에서 자기 및 자기저항의 접합크기 의존성

Junction Size Dependence of Magnetic and Magnetotransport Properties in MTJs

상카라나라얀^{1, 2}, 호영강¹, 김철기^{1, †}, 김종오¹, 이의복³

¹충남대학교 공과대학 재료공학과
²물리연구소 전기재료부, 인도
³공주대학교 사범대학 물리학과

V.K. Sankaranarayanan^{1, 2}, Yongkang Hu¹, CheolGi Kim^{1, †}, Chong-Oh Kim¹, and Heebok Lee³

¹Department of Materials Science and Engineering, Chungnam National University, Daejeon, 305-764, Korea
²Microstructure Devices Group, Science and Electronics Materials Division, National Physical Laboratory, Dr. KS. Krishnan Marg, New Delhi-110012, India
³Department of Pysics Education, Kongju National University, Kongju, 314-701, Korea

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Magneto-optic Kerr Effect(MOKE), AFM and magnetoresistance measurements have been carried out on as-deposited and annealed Magnetic Tunnel Junctions(MTJs) with junction sizes 180, 250, 320 and 380 μm in order to investigate the correlation among interlayer exchange coupling, surface roughness and junction size. Relatively irregular variations of coercivity H c (∼17.5 Oe) and interlayer exchange coupling H E (∼17.5 Oe) are observed over the junction in as-deposited sample prepared by DC magnetron sputtering. After annealing at 200 ? C , H c decreases to 15 Oe, while H E increases to 20 Oe with smooth local variation. H E shows very good correlation with surface roughness across the junction in agreement with Neel's orange peel coupling. The increasing slope per μm of normalized H c and H E are same near junction edge along free-layer direction irrespective of junction size, giving relatively uniform H c and H E for wider junction size. Thickness profiles of the junctions measured with α -step show increasingly flat top surface for larger junctions, indicating better uniformity for large. junctions in agreement with the normalized H c and H / E curves. TMR ratios also increase with increasing junction size, indicating improvement for larger uniform junctions.

Keywords:civity;Exchange coupling;MTJ;Size effect

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[1] Parkin SSP, Roche KP, Samant MG, Rice PM, Beyers RB, Scheuerlein RE, OiSullivan EJ, Brown SL, Bucchigano J, Abraham DW, Lu Y, Rooks M, Trouilloud PL, Wanner RA, Gallagher WJ, J. Appl. Phys., 85, 5828 (1999)

[2] Moodera JS, Kinder LR, Wong TM, Meservey R, Phys. Rev. Lett., 74, 3273 (1995)

[3] Miyazaki T, Tezuka N, J. Magn. Magn. Mater., 139, L231 (1995)

[4] Kim CG, Shoyama T, Tsunoda M, Takahashi M, Lee TY, Kim CO, Korean J. Magnetics, 7, 72 (2002)

[5] Julliere M, Phys. Lett., 54A, 225 (1975)

[6] Slonczewski JC, Phys. Rev. B, 39, 6995 (1989)

[7] Moodera JS, Kinder LR, Nowak J, LeClair P, Meservey R, Appl. Phys. Lett., 69, 708 (1996)

[8] Cools JCS, Kula W, Mauri D, Lin T, J. Appl. Phys., 85, 4466 (1999)

[9] Tsunoda M, Nishigawa K, Ogata S, Takahashi M, Appl. Phys. Lett., 80, 3135 (2002)

[10] Mahan JE, Physical vapor deposition of thin films, A Wiley-Interscience Publication, 2000, Ch. VII.5 (2000)