Nanomaterials 2014, 4(1), 46-54; doi:10.3390/nano4010046
Article

Effect of Low-Frequency AC Magnetic Susceptibility and Magnetic Properties of CoFeB/MgO/CoFeB Magnetic Tunnel Junctions

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Received: 14 November 2013; in revised form: 19 December 2013 / Accepted: 24 December 2013 / Published: 2 January 2014
(This article belongs to the Special Issue Magnetic Nanomaterials)
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract: In this investigation, the low-frequency alternate-current (AC) magnetic susceptibility (χac) and hysteresis loop of various MgO thickness in CoFeB/MgO/CoFeB magnetic tunneling junction (MTJ) determined coercivity (Hc) and magnetization (Ms) and correlated that with χac maxima. The multilayer films were sputtered onto glass substrates and the thickness of intermediate barrier MgO layer was varied from 6 to 15 Å. An experiment was also performed to examine the variation of the highest χac and maximum phase angle (θmax) at the optimal resonance frequency (fres), at which the spin sensitivity is maximal. The results reveal that χac falls as the frequency increases due to the relationship between magnetization and thickness of the barrier layer. The maximum χac is at 10 Hz that is related to the maximal spin sensitivity and that this corresponds to a MgO layer of 11 Å. This result also suggests that the spin sensitivity is related to both highest χac and maximum phase angle. The corresponding maximum of χac is related to high exchange coupling. High coercivity and saturation magnetization contribute to high exchange-coupling χac strength.
Keywords: magnetic tunnel junctions (MTJs); exchange coupling; low-frequency alternate-current (AC) magnetic susceptibility (χac); resonance frequency (fres)
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MDPI and ACS Style

Chen, Y.-T.; Lin, S.-H.; Sheu, T.-S. Effect of Low-Frequency AC Magnetic Susceptibility and Magnetic Properties of CoFeB/MgO/CoFeB Magnetic Tunnel Junctions. Nanomaterials 2014, 4, 46-54.

AMA Style

Chen Y-T, Lin S-H, Sheu T-S. Effect of Low-Frequency AC Magnetic Susceptibility and Magnetic Properties of CoFeB/MgO/CoFeB Magnetic Tunnel Junctions. Nanomaterials. 2014; 4(1):46-54.

Chicago/Turabian Style

Chen, Yuan-Tsung; Lin, Sung-Hao; Sheu, Tzer-Shin. 2014. "Effect of Low-Frequency AC Magnetic Susceptibility and Magnetic Properties of CoFeB/MgO/CoFeB Magnetic Tunnel Junctions." Nanomaterials 4, no. 1: 46-54.

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