Effect of Interface Roughness on Magnetoresistance and Magnetization Switching in Double-Barrier Magnetic Tunnel Junction

• Published in: IEEE transactions on magnetics Vol. 45; no. 6; pp. 2396 - 2398
• Main Authors: Hwang, J.Y., Lee, S.Y., Lee, N.I., Yim, H.I., Kim, M.Y., Lee, W.C., Rhee, J.R., Chun, B.S., Kim, T.W., Kim, Y.K., Lee, S.S., Hwang, D.G., Ri, E.J.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: New York, NY IEEE 01.06.2009; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Amorphous ferromagnetic; Amorphous materials; Bias; bias voltage dependence; CoFeSiB; Couplings; Cross-disciplinary physics: materials science; rheology; Electric potential; Exact sciences and technology; Ferromagnetism; Interface roughness; Iron; Magnetic switching; magnetic tunnel junction; Magnetic tunneling; Magnetism; Magnetization; Magnetoresistance; Magnetoresistivity; Materials science; Other topics in materials science; Physics; Reflectivity; Transmission electron microscopy; Tunnel junctions; Tunneling magnetoresistance; Voltage; Interfaces; magnetic tunnel junction; bias voltage dependence; Magnetization; CoFeSiB; Roughness; Magnetoresistance; Amorphous ferromagnetic; Surface states; Switching; Magnetic properties; Tunnels
• ISSN: 0018-9464; 1941-0069
• DOI: 10.1109/TMAG.2009.2018586

The three kinds of double-barrier magnetic tunnel junction (DMTJ) with or without amorphous ferromagnetic Co 70.5 Fe 4.5 Si 15 B 10 (in at. %) free-layer were investigated to understand the effect of the free-layer on the bias voltage dependence of tunneling magnetoresistance (TMR) ratio. The DMTJ structure consisted of Ta 45/Ru 9.5/IrMn 10/CoFe 7/AlO x /free-layer 7/AlO x /CoFe 7/IrMn 10/Ru 60 (thickness in nm). Various free layers, such as CoFe 7, CoFeSiB 7, and CoFe 1.5/CoFeSiB 4/CoFe 1.5 were prepared and compared. The roughness values of the interface between free-layer and tunnel barrier were confirmed by using the techniques of X-ray reflectivity and transmission electron microscopy. As a result, the amorphous free-layer made the interface roughness of DMTJ smoother, reducing the interlayer coupling field and suppressing the bias voltage dependence of TMR ratio at a given voltage.