Methods and systems for writing to magnetic memory devices utilizing alternating current
First Claim
1. A method comprising:
- in a memory device including two or more magnetic tunnel junctions (MTJs) including a first magnetic tunnel junction (MTJ) and a second MTJ arranged in series with respect to a single terminal of a transistor, wherein;
the first MTJ has a first magnetic anisotropy and the second MTJ has a second magnetic anisotropy distinct from the first magnetic anisotropy;
the first MTJ has a first write assist frequency and the second MTJ has a second write assist frequency that is distinct from the first write assist frequency;
the first write assist frequency is based on the first magnetic anisotropy; and
the second write assist frequency is based on the second magnetic anisotropy;
writing to a respective MTJ of the first MTJ and the second MTJ, including;
applying a DC current through the first MTJ and the second MTJ arranged in series with respect to the single terminal of the transistor; and
applying an AC current to the first MTJ and the second MTJ, wherein the AC current is adjusted to a frequency that is tuned to a write assist frequency corresponding to the respective MTJ; and
rewriting an initial value of a bit stored in the respective MTJ to a desired value of the bit, including;
identifying the respective MTJ that is storing the initial value of the bit as the first MTJ;
adjusting the AC current to a first AC current having a frequency that is tuned to the first write assist frequency corresponding to the first MTJ;
applying the first AC current to the two or more MTJs;
applying the DC current to the two or more MTJs; and
changing the initial value of the bit to the desired value of the bit by changing a magnetic state of the first MTJ without changing the magnetic state of the second MTJ.
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Accused Products
Abstract
A method for selectively writing to STT-MRAM using an AC current is provided. The method is performed in a memory device including two or more multilevel magnetic tunnel junctions (MTJs) arranged in series with respect to a single terminal of a transistor, where the two or more multilevel MTJs include a first MTJ having a first magnetic characteristic and first electrical characteristic and a second MTJ having a second magnetic characteristic that is distinct from the first magnetic characteristic and a second electrical characteristic. The method includes writing to an MTJ. The writing includes applying a DC current to the two or more MTJs and applying an AC current to the two or more MTJs, where the AC current is adjusted to a frequency that is tuned to a write assist frequency corresponding to the respective MTJ.
139 Citations
14 Claims
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1. A method comprising:
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in a memory device including two or more magnetic tunnel junctions (MTJs) including a first magnetic tunnel junction (MTJ) and a second MTJ arranged in series with respect to a single terminal of a transistor, wherein; the first MTJ has a first magnetic anisotropy and the second MTJ has a second magnetic anisotropy distinct from the first magnetic anisotropy; the first MTJ has a first write assist frequency and the second MTJ has a second write assist frequency that is distinct from the first write assist frequency; the first write assist frequency is based on the first magnetic anisotropy; and the second write assist frequency is based on the second magnetic anisotropy; writing to a respective MTJ of the first MTJ and the second MTJ, including; applying a DC current through the first MTJ and the second MTJ arranged in series with respect to the single terminal of the transistor; and applying an AC current to the first MTJ and the second MTJ, wherein the AC current is adjusted to a frequency that is tuned to a write assist frequency corresponding to the respective MTJ; and rewriting an initial value of a bit stored in the respective MTJ to a desired value of the bit, including; identifying the respective MTJ that is storing the initial value of the bit as the first MTJ; adjusting the AC current to a first AC current having a frequency that is tuned to the first write assist frequency corresponding to the first MTJ; applying the first AC current to the two or more MTJs; applying the DC current to the two or more MTJs; and changing the initial value of the bit to the desired value of the bit by changing a magnetic state of the first MTJ without changing the magnetic state of the second MTJ. - View Dependent Claims (2, 3, 8, 9, 10, 11, 12, 13, 14)
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4. A method comprising:
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in a memory device including two or more magnetic tunnel junctions (MTJs) including a first magnetic tunnel junction (MTJ) and a second MTJ arranged in series with respect to a single terminal of a transistor, wherein; the first MTJ has a first magnetic characteristic and a first electrical characteristic; and the second MTJ has a second magnetic characteristic that is distinct from the first magnetic characteristic and a second electrical characteristic; writing to a respective MTJ of the first MTJ and the second MTJ, including; applying a DC current through the first MTJ and the second MTJ arranged in series with respect to the single terminal of the transistor; and applying an AC current to the first MTJ and the second MTJ, wherein the AC current is adjusted to a frequency that is tuned to a write assist frequency corresponding to the respective MTJ, wherein; the first MTJ has a first size and the second MTJ has a second size; the first MTJ has a first Resistance-Area (RA) product and the second MTJ has a second RA product; the first electrical characteristic is based on the first RA product and the first size of the first MTJ; and the second electrical characteristic is based on the second RA product and the second size of the second MTJ; and rewriting an initial value of a bit stored in the respective MTJ to a desired value of the bit, including; identifying the respective MTJ that is storing the initial value of the bit as the first MTJ; adjusting the AC current to a first AC current having a frequency that is tuned to the first write assist frequency corresponding to the first MTJ; applying the first AC current to the two or more MTJs; applying the DC current to the two or more MTJs; and changing the initial value of the bit to the desired value of the bit by changing a magnetic state of the first MTJ without changing the magnetic state of the second MTJ. - View Dependent Claims (5, 6, 7)
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Specification