A Method of Controlling Free Layer Domain Structure to Realize Ten-state Data Storage in Magnetic Tunnel Junction

Abstract

The invention relates to a method for controlling the domain structure of a free layer to realize ten-state data storage in a magnetic tunnel junction, comprising: (1) measuring the hysteresis loop of the magnetic tunnel junction to find out the initial magnetic field; (2) in the direction of the negative magnetic field Apply an initial magnetic field to the magnetic tunnel junction; (3) apply a positive direction magnetic field to the magnetic tunnel junction, and increase the positive direction magnetic field to the writing magnetic field at an increase rate of 0-200 Oersted / s through the No overshot mode, and obtain A certain multi-magnetic domain state; (4) changing the size of the write magnetic field, and performing steps (2) to (3) to obtain another multi-magnetic domain state; repeating this step until ten kinds of multi-magnetic domain states are obtained; (5) Ten kinds of multi-magnetic domain states are read out. The invention can be directly applied to the existing magnetic tunnel structure, and greatly expands the performance of the current magnetic tunnel junction. The invention has a good application prospect in high-density, low-power consumption novel spintronic memory.

Description

technical field [0001] The invention relates to a method for realizing ten-state data storage in a magnetic tunnel junction by controlling the domain structure of a free layer, and belongs to the field of data storage of information technology. Background technique [0002] In order to meet the increasing demand for data storage with non-volatile, high-density, low-power consumption and other excellent characteristics in consumer electronics and big data storage, researchers pin their hopes on multi-state non-volatile memory devices. In a multi-state memory device, a memory cell can record up to ten or even more values, instead of the current two values ​​of "0" and "1". Therefore, polymorphic data storage can not only greatly improve data storage density, but also promote the rapid development of neural networks and artificial intelligence. [0003] At present, the main ways to realize multi-state non-volatile storage experimentally are as follows: first, use the phase cha...

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Problems solved by technology

This patent discloses that "Magnetic Tunnel Junction (MTJ) has a ferromagnetic free layer, and the ferromagnetic free layer has multiple magnetic domains that can be independently programmed to a predetermined magnetization". Composed of two different regions, relying on shape anisotropy to maintain an independent magnetic domain structure, this design has the following disadvantages: 1. The sample preparation will be very complicated, and the free layer itself needs to be designed into regions of different sizes and shapes; 2. Generally, the shape anisotropy of the material is relatively small. If the stability is to be good, the difference in shape and size of the two regions needs to be increased, which will inevitably lead to a larger device size, which is difficult to meet the needs of high-density storage.

When the difference between the two regions is small, the difference in coercivity between the two regions will become smaller, which will inevitably lead to insufficient stability

3. In the embodiment, a single memory cell can only provide 4 stable resistance states. To realize more resistance states, the free layer needs to be composed of three or more regions with different shapes and sizes. Two flaws would be more significant and almost impossible to achieve

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