FeMn Exchange Biased Storage Layer for Thermally Assisted MRAM

Thermally assisted MRAM cells with FeMn exchange biased storage layers were successfully written using 50 ns current pulses with write power densities below 10 mW/¿m² and current densities below 1.3 ×10 ⁶ A/cm². These low power density values were achieved without using thermal barriers to confine the heat in the cell. Introducing thermal barriers would even further lower the write power density by increasing the heating efficiency. The storage layer coercivity increased upon anneal at 340 C. This could be related to manganese diffusion or to a texture incompatibility between the CoFe and the FeMn antiferromagnetic layer, a problem which can be fixed by insertion of appropriate diffusion barrier or texture control layer. Successful writing was observed for repeated write attempts with heating pulse power densities in the 7-12.5 mW/¿m² range.