Specifically, if the electrons flowing into a layer have to change their spin, this will develop a torque that will be transferred to the nearby layer, this lowers the amount of current needed to write the cells, making it about the same as the read process.There are concerns that the "classic" type of MRAM cell will have difficulty at high densities due to the amount of current needed during writes, a problem that STT avoids, for this reason, the STT proponents expect the technique to be used for devices of 65 nm and smaller.Magnetoresistive random-access memory (MRAM) is a non-volatile random-access memory technology available today that began its development in the 1990s.Continued increases in density of existing memory technologies – notably flash RAM and DRAM – kept it in a niche role in the market, but its proponents believe that the advantages are so overwhelming that magnetoresistive RAM will eventually become a dominant type of memory, potentially even becoming a universal memory.
The elements are formed from two ferromagnetic plates, each of which can hold a magnetization, separated by a thin insulating layer.
However, the write process requires more power to overcome the existing field stored in the junction, varying from three to eight times the power required during reading, although the exact amount of power savings depends on the nature of the work – more frequent writing will require more power – in general MRAM proponents expect much lower power consumption (up to 99% less) compared to DRAM.
STT-based MRAMs eliminate the difference between reading and writing, further reducing power requirements.
A particular cell is (typically) selected by powering an associated transistor that switches current from a supply line through the cell to ground.
Due to the Tunnel magnetoresistance, the electrical resistance of the cell changes due to the relative orientation of the magnetization in the two plates.