Multiple-bits-per-cell voltage-controlled magnetic memory

摘要

Voltage controlled magneto-electric tunnel junctions and memory devices are described which provide efficient high speed voltage switching of non-volatile magnetic devices (MeRAM) at high cell densities. A multi-bit-per-cell (MBPC) MeRAM is described which requires only a single transistor to write and read two data bits from the one MBPC MeRAM cell.

主权项

1. A voltage-controlled magnetic anisotropy (VCMA) switch apparatus, comprising:
at least three ferromagnetic (FM) layers having at least one FM fixed layer and at least a first FM free layer, and a second FM free layer; and a dielectric (DE) layer interposed between each of said FM layers separating them from one another; wherein material, shape and thickness of said FM free layers and said FM fixed layer are selected to have in-plane (IP) and out-of-plane (OOP) anisotropies; wherein OOP anisotropy of said FM free layers is affected by interface properties between said FM layers and said DE layers, and is controlled by voltages applied across said DE layers as an applied voltage and polarity; wherein a magnetization orientation of said first FM free layer is switched in response to voltages of a first polarity, while magnetization orientation of said second FM free layer is switched in response to voltages of a second polarity by utilizing a voltage-controlled magnetic anisotropy (VCMA) effect; wherein said apparatus is configured for precessional motion of magnetization; wherein said magnetization orientation of said first FM free layer is changed in response to width of a pulse of a voltage level of a first polarity and said second FM free layer is changed in response to width of a pulse of a voltage level of a second polarity; and wherein width of each said pulse is timed at approximately one-half of the precessional period of each said FM free layer.