Logic unit including magnetic tunnel junction elements having two different anti-ferromagnetic layers

摘要

A logic unit for security engines or content addressable memory including Magnetic Tunnel Junction (MTJ) elements connected in series to form a NAND-type string, where each MTJ element includes a storage layer and a sense layer having different anti-ferromagnetic materials respectively having higher and lower blocking temperatures. During write/program, the string is heated above the higher blocking temperature, and magnetic fields are used to store bit values of a confidential logical pattern in the storage layers. The string is then cooled to an intermediate temperature between the higher and lower blocking temperatures and the field lines turned off to store bit-bar (opposite) values in the sense layers. During a pre-compare operation, the MTJ elements are heated to the intermediate temperature, and an input logical pattern is stored in the sense layers. During a compare operation, with the field lines off, a read current is passed through the string and measured.

主权项

1. A logic unit comprising:
a plurality of Magnetic Tunnel Junction (MTJ) elements connected in series, each said MTJ element comprising:
a storage layer including a first antiferromagnetic structure contacting a first ferromagnetic structure, the first antiferromagnetic structure comprising a first material having a first blocking temperature;a sense layer including a second antiferromagnetic structure contacting a second ferromagnetic structure, the second antiferromagnetic structure comprising a second antiferromagnetic material having a second blocking temperature; anda tunnel dielectric layer disposed between the first ferromagnetic structure of the storage layer and the second ferromagnetic structure of the sense layer,wherein the first blocking temperature of the first antiferromagnetic material is greater than the second blocking temperature of the second antiferromagnetic material; a select transistor that is coupled in series with the plurality of MTJ elements between a voltage source and a ground terminal; and a controller configured to control the select transistor such that: during a first time period, said select transistor is activated to generate a first heating current that passes through said plurality of MTJ elements between said voltage source and said ground terminal, wherein said first heating current is generated such that said plurality of MTJ elements are heated to a first temperature above said first blocking temperature of the first antiferromagnetic material; and during a second time period, said select transistor is activated to generate a second heating current that passes through said plurality of MTJ elements between said voltage source and said ground terminal, wherein said second heating current is generated such that said plurality of MTJ elements are heated to a second temperature between said first blocking temperature and said second blocking temperature of the second antiferromagnetic material.