Extremely fast MRAM data storage within reach

March 8, 2011
This is an electron-microscopic recording of an MRAM storage cell. Credit: (Fig.: PTB)

Magnetic Random Access Memories (MRAM) are the most important new modules on the market of computer storage devices. Like the well known USB-sticks, they store information into static memory, but MRAM offer short access times and unlimited writing properties. Commercial MRAMs have been on the market since 2005. They are, however, still slower than the competitors they have among the volatile storage media.

An invention made by the Physikalisch-Technische Bundesanstalt (PTB, Germany) changes this situation: A special chip connection, in association with dynamic triggering of the component, reduces the response from - so far - 2 ns to below 500 ps. This corresponds to a data rate of up to 2 GBit (instead of the approx. 400 MBit so far). and the thermal load will be reduced, as well as the bit error rate. The European patent is just being granted this spring; the US patent was already granted in 2010. An industrial partner for further development and manufacturing such MRAMs under licence is still being searched for.

Fast computer storage chips like DRAM and SRAM (Dynamic and Static Random Access Memory) which are commonly used today, have one decisive disadvantage: in the case of an interruption of the power supply, the information stored on them is irrevocably lost. The MRAM promises to put an end to this. In the MRAM, the digital information is not stored in the form of an electric charge, but via the magnetic alignment of storage cells (magnetic spins). MRAMs are very universal storage chips because they allow - in addition to the non-volatile information storage - also faster access, a high integration density and an unlimited number of writing and reading cycles.

However, the current MRAM models are not yet fast enough to outperform the best competitors. The time for programming a magnetic bit amounts to approx. 2 ns. Whoever wants to speed this up, reaches certain limits which have something to do with the fundamental physical properties of magnetic storage cells: during the programming process, not only the desired storage cell is magnetically excited, but also a large number of other cells. These excitations – the so-called magnetic ringing – are only slightly attenuated, their decay can take up to approx. 2 ns, and during this time, no other cell of the MRAM chip can be programmed. As a result, the maximum clock rate of MRAM is, so far, limited to approx. 400 MHz. Until now, all experiments made to increase the velocity have led to intolerable write errors.

Now, PTB scientists have optimized the MRAM design and integrated the so-called ballistic bit triggering which has also been developed at PTB. Here, the magnetic pulses which serve for the programming are selected in such a skilful way that the other cells in the MRAM are hardly magnetically excited at all. The pulse ensures that the magnetization of a cell which is to be switched performs half a precision rotation (180°), while a cell whose storage state is to remain unchanged performs a complete precision rotation (360°). In both cases, the magnetization is in the state of equilibrium after the magnetic pulse has decayed, and magnetic excitations do not occur any more.

This optimal bit triggering also works with ultra-short switching pulses with a duration below 500 ps. The maximum clock rates of the MRAM are, therefore, above 2 GHz. In addition, several bits can be programmed at the same time which would allow the effective write rate per bit to be increased again by more than one order. This invention allows clock rates to be achieved with MRAM which can compete with those of the fastest volatile storage components.

Explore further: Toshiba and NEC Develop World's Fastest, Highest Density MRAM

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not rated yet Mar 08, 2011
Lets put it this way. The new mram chip developed here runs slightly faster than your regular memory (sram,dram, etc.) Since it doesn't need constant electricity to keep it's information, you won't need to boot up your computer...just turn it on, and presto - computer is on.

can I get a hard drive made from this??!

2 / 5 (1) Mar 08, 2011
Do relatively weak magnetic fields damage the data in this storage form?
5 / 5 (1) Mar 08, 2011
Do relatively weak magnetic fields damage the data in this storage form?

What do you mean by relatively? It's probably safe to assume that a similar device that uses similar principles at similar sizes (IE a single magnetic bit in a hard drive) would be similarly shielded and affected by stray magnetic fields. The storage method is very similar (magnetic polarity vs magnetic spin), and the main difference is the method of read/write.

It should work fine under normal use, and putting a magnet right up to it is probably a bad idea.
1.2 / 5 (6) Mar 08, 2011
I'll take this any day over those crappy Nand Chips...they have so much error correction chips just just to provide basic reliability. Brings these babies to market for Hard Drive and Standard Memory and that will be as close as a quantum leap to computers that consumers will see in the near future. Intel will keep using silicon till like 5 nm which is 5-6 years away due to competition from AMD. Otherwise they would release it 10 years from now. Then they'll use something similar to silicon; no not Graphene because of band cap. Optical chips are still 15 years away from consumer reality. Quantum chips will never be in our hands; too much power...Government has to stay on top.
not rated yet Mar 09, 2011

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