637 research outputs found
Ultrafast and low-energy switching in voltage-controlled elliptical pMTJ
Switching magnetization in a perpendicular magnetic tunnel junction (pMTJ)
via voltage controlled magnetic anisotropy (VCMA) has shown the potential to
markedly reduce the switching energy. However, the requirement of an external
magnetic field poses a critical bottleneck for its practical applications. In
this work, we propose an elliptical-shaped pMTJ to eliminate the requirement of
providing an external field by an additional circuit. We demonstrate that a 10
nm thick in-plane magnetized bias layer (BL) separated by a metallic spacer of
3 nm from the free layer (FL) can be engineered within the MTJ stack to provide
the 50 mT bias magnetic field for switching. By conducting macrospin
simulation, we find that a fast switching in 0.38 ns with energy consumption as
low as 0.3 fJ at a voltage of 1.6 V can be achieved. Furthermore, we study the
phase diagram of switching probability, showing that a pulse duration margin of
0.15 ns is obtained and a low-voltage operation (~ 1 V) is favored. Finally,
the MTJ scalability is considered, and it is found that scaling-down may not be
appealing in terms of both the energy consumption and the switching time for
the precession based VCMA switching.Comment: There are 28 pages and 5 figure
RRAM variability and its mitigation schemes
Emerging technologies such as RRAMs are attracting significant attention due to their tempting characteristics such as high scalability, CMOS compatibility and non-volatility to replace the current conventional memories. However, critical causes of hardware reliability failures, such as process variation due to their nano-scale structure have gained considerable importance for acceptable memory yields. Such vulnerabilities make it essential to investigate new robust design strategies at the circuit system level. In this paper we have analyzed the RRAM variability phenomenon, its impact and variation tolerant techniques at the circuit level. Finally a variation-monitoring circuit is presented that discerns the reliable memory cells affected by process variability.Peer ReviewedPostprint (author's final draft
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