MRAM (Magnetoresistive Random Access Memory)

        MRAM (Magnetoresistive Random Access Memory) is a system of storing knowledge bits using magnetic charges in lieu of the electrical charges used by DRAM (dynamic random access memory). Scientists define a metal as magnetoresistive if it shows a slight alter in electrical resistance when placed in a magnetic field. By combining the high speed of static RAM & the high density of DRAM, proponents say MRAM could be used to significantly improve electronic products by storing greater amounts of knowledge, enabling it to be accessed faster while consuming less battery power than existing electronic memory.
        MRAM, however, retains knowledge after a power supply is cut off. Replacing DRAM with MRAM could prevent knowledge loss & enable computers that start instantly, without waiting for program to boot up.
        Unlike conventional RAM chip technologies, in MRAM information is not stored as electric charge or current flows, but by magnetic storage elements. The elements are formed from two ferromagnetic plates, each of which can hold a magnetic field, separated by a narrow insulating layer. of the plates is a permanent magnet set to a specific polarity, the other's field can be changed to match that of an outside field to store memory. This configuration is called a spin valve and is the simplest structure for a MRAM bit. A memory device is built from a grid of such "cells".
        The simplest system of reading is accomplished by measuring the electrical resistance of the cell. A specific cell is (usually) chosen by powering an associated transistor which switches current from a supply line through the cell to ground. Due to the magnetic tunnel effect, the electrical resistance of the cell changes due to the orientation of the fields in the plates. By measuring the resulting current, the resistance inside any particular cell can be determined, & from this the polarity of the writable plate. Usually if the plates have the same polarity this is thought about to mean "1", while if the plates are of opposite polarity the resistance will be higher & this means "0".