Thermal Assisted Switching, or TAS, is one of the new 2nd generation approaches to MRAM

MRAM

Magnetoresistive Random-Access Memory is a non-volatile computer memory technology that has been under development since 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...

 currently being developed. A few different designs have been proposed, but all rely on the idea of reducing the required switching fields by heating. The first design’s cell, which was proposed by Daughton and co-workers, had a heating element, an MRAM

MRAM

Magnetoresistive Random-Access Memory is a non-volatile computer memory technology that has been under development since 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...

 bit, an orthogonal digit line, and used a low Curie point

Curie point

In physics and materials science, the Curie temperature , or Curie point, is the temperature at which a ferromagnetic or a ferrimagnetic material becomes paramagnetic on heating; the effect is reversible. A magnet will lose its magnetism if heated above the Curie temperature...

 ferromagnetic material as the storage layer. In a second and more promising design, which was developed by the Spintec Laboratory (France) and subsequently licensed to Crocus Technology

Crocus Technology

Crocus Technology, founded in 2004, is a venture-capital-backed semiconductor startup company developing next generation magnetoresistive random access memory technology. The company's products originated in a Grenoble-based Spintec laboratory...

, the storage layer is made of a ferromagnetic and an antiferromagnetic layer. When the cell is heated by flowing a heating current through the junction and the temperature exceeds the “blocking temperature” (T_b), the ferromagnetic layer is freed and the data is written by application of a magnetic field while cooling down. When idle, the cell’s temperature is below the blocking temperature and much more stable.

This approach offers multiple advantages over previous MRAM

MRAM

Magnetoresistive Random-Access Memory is a non-volatile computer memory technology that has been under development since 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...

 technologies:

(a) Because the write selection is temperature driven, it eliminates write selectivity problems,

(b) It is a low-power approach as only one magnetic field is required to write and because the cell stability and magnetic susceptibility are decoupled as a result of the introduction of the blocking temperature,

(c) It is thermally stable due to the exchange bias

Exchange bias

Exchange bias or exchange anisotropy occurs in bilayers of magnetic materials where the hard magnetization behavior of an antiferromagnetic thin film causes a shift in the soft magnetization curve of a ferromagnetic film...

of the storage layer.