The invention discloses a magnetic
random access memory (MRAM) and a writing method, a reading method and a preparation method thereof. The
magnetic RAM includes a substrate layer, a ferroelectric layer, a composite anti-ferromagnetic structure, a first
isolation layer and a first ferromagnetic layer that are successively stacked. The composite anti-ferromagnetic structure is the free layer of theMRAM. The first ferromagnetic layer is the fixed layer of the MRAM. The ferroelectric layer is subjected to polarization or lattice
distortion under the effect of applied
voltage in order to change the
coupling state of the composite anti-ferromagnetic structure. The first ferromagnetic layer has a constant first
magnetic moment direction. The first
isolation layer is configured to control the first
magnetic moment direction not to be affected by the
coupling state of the composite anti-ferromagnetic structure. The MRAM achieves writing by using the transformation of ferromagnetic
coupling and anti-ferromagnetic coupling of the composite anti-ferromagnetic structure under the effect of an
electric field, and solves a problem that the MRAM has a
large size and a low storage density becauseof a large
line width during the writing achieved by the induction
magnetic field or polarization current of a wire.