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▲ [20p-B101-5] Reduction of Write Error Rate in Voltage-Induced Heavily-Damped Precessional Switching by Elliptic Cylinder Shaped Recording Layer
Keywords:spintronics, MRAM, magnetic anisotropy
Voltage-induced dynamic switching in magnetic tunnel junction (MTJ) is a writing technique for voltage-controlled magnetoresistive random access memory (VC-MRAM), which is expected to be an ultimate non-volatile memory with ultra-low power consumption [1-5]. In conventional dynamic switching, the width of sub-nanosecond write voltage pulse must be precisely controlled to achieve a sufficiently low write error rate (WER). This very narrow tolerance of pulse width is the biggest technical difficulty in developing VC-MRAM. Recently we proposed the heavily-damped precessional switching based writing scheme of the voltage-controlled MTJ where the WER was insensitive to pulse width, although the WER was too high for memory applications [6]. To broaden the application areas of the VC-MRAM, it is necessary to find a method to improve the WER.
In this study [7], we theoretically show that the WER in the elliptic cylinder shaped MTJ (elliptic MTJ) can be several orders of magnitude smaller than that in the circular cylinder shaped MTJ (circular MTJ) when the external magnetic field is applied parallel to the minor axis of the ellipse. The reduction of the WER is due to narrowing of the magnetization distribution perpendicular to the plane direction immediately before the voltage is applied.
This presentation was partly based on results obtained from a project, JPNP16007, commissioned by the New Energy and Industrial Technology Development Organization (NEDO), Japan.
[1] Y. Shiota et al., Nat. Mater., Vol. 11, p. 39 (2012). [2] S. Kanai et al., APL, Vol. 101, p. 122403 (2012). [3] C. Grezes et al., APL, Vol. 108, p. 012403 (2016). [4] Y. Shiota et al., APEX, Vol. 9, p. 013001 (2016). [5] T. Yamamoto et al., J. Phys. D: Appl. Phys., Vol. 52, p. 164001 (2019). [6] R. Matsumoto et al., APEX, Vol.12, 053003 (2019). [7] R. Matsumoto et al., submitted.
In this study [7], we theoretically show that the WER in the elliptic cylinder shaped MTJ (elliptic MTJ) can be several orders of magnitude smaller than that in the circular cylinder shaped MTJ (circular MTJ) when the external magnetic field is applied parallel to the minor axis of the ellipse. The reduction of the WER is due to narrowing of the magnetization distribution perpendicular to the plane direction immediately before the voltage is applied.
This presentation was partly based on results obtained from a project, JPNP16007, commissioned by the New Energy and Industrial Technology Development Organization (NEDO), Japan.
[1] Y. Shiota et al., Nat. Mater., Vol. 11, p. 39 (2012). [2] S. Kanai et al., APL, Vol. 101, p. 122403 (2012). [3] C. Grezes et al., APL, Vol. 108, p. 012403 (2016). [4] Y. Shiota et al., APEX, Vol. 9, p. 013001 (2016). [5] T. Yamamoto et al., J. Phys. D: Appl. Phys., Vol. 52, p. 164001 (2019). [6] R. Matsumoto et al., APEX, Vol.12, 053003 (2019). [7] R. Matsumoto et al., submitted.