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Top1. Introduction To Mram
MRAM stands for Magneto-resistive Random Access Memory. It is used to store the information with the help of magnetic field and the stored information can be retained or read after many years without any damage due to its non-volatility property. Non-Volatile Memory (NVM) is a sort of processor memory which can preserve the stowed data stably when the power is disconnected, whereas volatile needs continuous power to hold the data. MRAMs (Slaughter et al., 2002) described as a memory which utilize Magneto-resistance effect for the reading theory but not considering the writing principles. There are different type’s magneto resistance effect like AMR, GMR and TMR. Popularize MRAM utilizeTMR (Tunnel Magneto-resistance Effect) and Junction which have TMR effect is named as MTJs. (Apalkov et al., 2016) (Bhatti et al., 2017)
Figure 1.
Arrangements of MRAM based on MTJ device
The MRAM prime arrangements are based on MTJ (Magnetic Tunnel Junction) (Zhang et al., 2020) is an active device in which the double Ferro-Magnetic films are detached by the insulated film. This insulating layer is called as Tunnel barrier see figure 1.The AlOx material is use to formed the tunnel barrier because it provides the large tunneling magneto-resistance effect in the MTJ at the ambient temperature and its spin dependent tunneling transfer characteristics brings curiosity on a huge scale ensuring the biggest Magneto-resistance (MR) ratio of 81%at RT and 107% at 4.2 k in AlOx based tunnel junctions. The various types of Al-O barrier based, between the two layer of metal in MTJ's such as spin valve type pinned MTJ, double barrier magnetic tunnel junction (DBMTJ), Half-metal MTJ, perpendicular anisotropic MTJ, diluted magnetic semiconductor composite MTJ, superconductors composite MTJ, granular film composite MTJ and Nano ring shaped MTJ. In MJT, lowresistance (Rp) is experienced when the magnetization in both Ferro-magnetic layer is parallel, the electrons simply cross the tunnel barrier from one layer to another. On the other hand, highresistance (Rap) is experienced when the magnetization in both magnetic layer is anti-parallel and electrons cannot cross the barrier easily from one layer to another. As MTJ is TMR effect based junction play a vital role that is, it measurehow one can distinguish between high and low resistance states. Data can be kept as '1' mean high resistance state and '0' means low resistance state in the junction by controlling the magnetization of the layers and the data can be study by evaluating the resistance of junction. When the exterior electric filed is applied to the junction one can change or control the direction of the magnetization of the layer’s. For writing principle, the MRAM utilize the STT (Spin Transfer Torque) writing and termed as STT-MRAM, Spin RAM or, STT-RAM. (Dieny et al., 2017)
It offer non-volatile speedy memory range which can be coupled quickly with processors, otherwise large volume system were used for the data storage. Presently, it has attained a guaranteed position in the industrial market. Many companies like Toshiba, Hitachi, IBM, Samsung and TSMC are vigorously expanding MRAM chip modified machinery. With next production memory technologies, MRAM is supposed to have the major market in the coming year, tracked by FeRAM, PCRAM and Memristors. In the last the uniqueness of the MRAM which make it differ from other memories are (Titu-Marius, 2018):
- 1.
It can maintain its information even when the applied power is switched off.
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It provide great read and write speed in contrast to other memories like Flash memory or EEPROM.
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It do not disintegrate with time.
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It utilize low power level relatively to other memories.