Method for detecting information stored in a MRAM cell having two magnetic layers in different thicknesses
AssigneeMotorola, Inc.
InventorsSaied N. Tehrani, Eugene Chen, Mark Durlam, Xiaodong T. Zhu
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Abstract
A method for detecting and storing four states contained in a MRAM cell having two layers (11,13) which have different thicknesses is provided. A first magnetic field is applied to the MRAM cell, which causes a magnetoresistive change in the MRAM cell. A first and second states are detected based on the magnetoresistive change. A second magnetic field is further applied to the MRAM cell. A third and fourth states are detected based on the magnetoresistive change due to the second magnetic field.
Claims25
In a magnetic random access memory (MRAM) cell having two switchable magnetic layers having different magnetic switching thresholds separated by a conductor layer, a method for detecting one of a first state, a second state, a third state and a fourth state stored in the MRAM cell comprising the steps of:
- applying a first magnetic field to the MRAM cell;
- sensing one of the first state and the second state in the MRAM cell in response to a change of a resistance due to the first magnetic field;
- applying a second different magnetic field to the MRAM cell;
- and
- sensing one of the third state and the fourth state in the MRAM cell in response to a change of a resistance due to the second magnetic field.
In a magnetic random access memory (MRAM) cell having two magnetic layers having different thicknesses separated by a conductor layer, a method for detecting one of a first state, a second state, a third state and a fourth state stored in the MRAM cell comprising the steps of:
- applying a first magnetic field to the MRAM cell;
- sensing one of the first state and the second state in the MRAM cell in response to a change of a resistance due to the first magnetic field;
- applying a second different magnetic field to the MRAM cell which is opposite to the first magnetic field in a direction and having the same strength as the first magnetic field;
- and
- sensing one of the third state and the fourth state in the MRAM cell in response to a change of a resistance due to the second magnetic field.
In a magnetic random access memory (MRAM) cell having two magnetic layers having different thicknesses separated by a conductor layer, a method for storing one of a first state, a second state, a third state and a fourth state in the MRAM cell comprising the steps of:
- switching magnetic vectors in both layers by applying a first magnetic field to the cell when the first state and the fourth state are stored in the cell;
- and
- switching magnetic vectors in both layers by applying the first magnetic field to the cell and then applying a second magnetic field to the cell when the second and third states are stored in the cell.
Dependencies are inferred from the claim text.