where $ E_{dissipation} \approx E_{switching} $ is the dissipation energy, which is also approximately equal switching energy.
notice that $ E_{barrier} $ is always around $1-1.5 eV$, so $\lambda$ is really determined by collective versus single-electron physics mechanism and the size of the cell (anything else basic?)
In another paper (Wang - Koester) , the authors argue that $ \lambda \approx 1 $ is achievable. In particular, GSHE looks better than stt-MRAM. AFM and TI (at room temperature) can make significant breakthroughs, especially when made commercial (no sooner than 5 years?).
for the electronic-charge switch, $\lambda $ is of order $ N_e \sim 400 $.
for stt-MRAM, $ \lambda_{stt-mram} > 1000 $ is indicated, while in 2014 (from Wang-Koester) we can see $ \lambda_{stt-mram} \approx 4 * 10^5 $. This means that basic STT-MRAM is not particularly energy-efficient. From the table on IMComputing page., the review in 2019 we can see $ \lambda_{stt-mram} \approx 10^4 $.
the summary - the smaller the dimensionless parameter $ \lambda $ is the better. This parameter must be larger than 1 for any classical switching. Different switching devices need to optimize this parameter, both CMOS and stt-mram are not at the possible, but very difficul physics-allowed, limit of this parameter.
excellent endurance of stt-MRAM (as well as commercial development)
stt-mram has the best endurance among emerging NVMs, still behind by 1-2 orders of magnitude from SRAM and DRAM, see IMComputing
Switching energy per write operation for stt-MRAM is a severe limitation due to $ \lambda_{stt-mram} > 1000 $
Write energy of stt-mram is about 2 orders of magnitude worse than for CMOS (1600 kT line). stt-mram does not have here advantage against charge-based DRAM and SRAM in spite of being “collective spintronic switch”. SRAM is about 2 orders better in write energy than stt-mram, as you can see from the picture above.
Topological Insulator and Sraintronics-based predicted to be very energy-efficient, but very far from being commercially ready (while in 2021y)
the challenge of switching speed
distinguish between theoretical and realised versions
stt-mram is the best among experimentally shown to work.
stt- mram is slightly behind in write/read speed than SRAM (the fastest), but close (within 1 order of magnitude).
AFM might become really good both in the switching energy category and the switching speed!
speed and energy efficiency are two main goals for computing (AI hardware), so far as cost, non-volatility, and endurance are satisfactory (from the point of view of business applications)
the picture below shows "the ideal collective spintronic switch"
The fundamental advantage of this approach over the semiconductor-based switch concept is its projected low operation energy.
Fig. 1 compares a generic spintronic switch and a generic electronic switch.
The picture might be misunderstood. stt-mram is NOT the “ideal collective spintronic switch”.
Which NVM-RAM is going to prove itself, even commercially, to be the “the ideal collective spintronic switch” in the (far?) future?
Defined in [the paper (Manipatruni-Nikonov)](https://knowen-production.s3.amazonaws.com/uploads/attachment/file/3731/Beyond%2BCMOS%2Bcomputing%2Bwith%2Bspin%2Band%2Bpolarization.pdf), the figure of merit $ \lambda $ for any tunneling junction/CMOS transistor/switch/MtJ
$$ \lambda = \frac{E_{dissipation}}{E_{barrier}} $$
where $ E_{dissipation} \approx E_{switching} $ is the dissipation energy, which is also approximately equal switching energy.
- notice that $ E_{barrier} $ is always around $1-1.5 eV$, so $\lambda$ is really determined by **collective versus single-electron physics mechanism and the size of the cell** (anything else basic?)
In [another paper (Wang - Koester)](https://knowen-production.s3.amazonaws.com/uploads/attachment/file/5071/a16-Wang-2j6mokh.pdf) , the authors argue that $ \lambda \approx 1 $ is achievable. In particular, GSHE looks better than stt-MRAM. AFM and TI (at room temperature) can make significant breakthroughs, especially when made commercial (no sooner than 5 years?).
- for the electronic-charge switch, $\lambda $ is of order $ N_e \sim 400 $.
- for stt-MRAM, $ \lambda_{stt-mram} > 1000 $ is indicated, while in 2014 (from Wang-Koester) we can see $ \lambda_{stt-mram} \approx 4 * 10^5 $. This means that **basic STT-MRAM is not particularly energy-efficient.** From the table on [IMComputing page.](https://knowen.org/nodes/27132), the review in 2019 we can see $ \lambda_{stt-mram} \approx 10^4 $.
> the summary - **the smaller the dimensionless parameter $ \lambda $ is the better.** This parameter must be larger than 1 for any classical switching. Different switching devices need to optimize this parameter, **both CMOS and stt-mram are not at the possible, but very difficul physics-allowed, limit of this parameter.**
# key figures from [the paper (Wang - Koester)](https://knowen-production.s3.amazonaws.com/uploads/attachment/file/5071/a16-Wang-2j6mokh.pdf)
- excellent endurance of stt-MRAM (as well as commercial development)
stt-mram has the best endurance among emerging NVMs, still behind by 1-2 orders of magnitude from SRAM and DRAM, see IMComputing
- Switching energy per write operation for stt-MRAM is a severe limitation due to $ \lambda_{stt-mram} > 1000 $
Write energy of stt-mram is about 2 orders of magnitude worse than for CMOS (1600 kT line). **stt-mram does not have here advantage against charge-based DRAM and SRAM in spite of being “collective spintronic switch”.** SRAM is about 2 orders better in write energy than stt-mram, as you can see from the picture above.
Topological Insulator and Sraintronics-based predicted to be very energy-efficient, but very far from being commercially ready (while in 2021y)
- the challenge of switching speed
distinguish between theoretical and realised versions
stt-mram is the best among experimentally shown to work.
stt- mram is slightly behind in write/read speed than SRAM (the fastest), but close (within 1 order of magnitude).
*AFM might become really good both in the switching energy category and the switching speed!*
- **speed and energy efficiency are two main goals for computing (AI hardware), so far as cost, non-volatility, and endurance are satisfactory (from the point of view of business applications)**
## the picture below shows "the ideal collective spintronic switch"
> The fundamental advantage of this approach over the semiconductor-based switch concept is its projected low operation energy.
> Fig. 1 **compares a generic spintronic switch and a generic electronic switch.**
The picture might be misunderstood. **stt-mram is NOT the “ideal collective spintronic switch”.**
## Which NVM-RAM is going to prove itself, even commercially, to be the “the ideal collective spintronic switch” in the (far?) future?
