Researchers build first 3D magnetic logic gate

August 8, 2014 by Lisa Zyga feature
Magnetic force microscope images of the 3D magnetic logic gates, each containing three input magnets and one output magnet. Numbers show the magnetization states of the output magnet for all input configurations. Credit: Eichwald, et al. ©2014 IOP

( —The integrated circuits in virtually every computer today are built exclusively from transistors. But as researchers are constantly trying to improve the density of circuits on a chip, they are looking at alternative ways to build circuits. One alternative method uses nano-sized magnets, in which the magnets possess two stable magnetic states that represent the logic states "0" and "1."

Until now, nanomagnetic logic (NML) has been implemented only in two dimensions. Now for the first time, a new study has demonstrated a 3D programmable magnetic logic gate, where the magnets are arranged in a 3D manner. In comparison to the 2D gate, the 3D arrangement of the magnets allows for an increase in the field interaction between neighboring magnets and offers higher integration densities.

The researchers, Irina Eichwald, et al., at the Technical University of Munich in Munich, Germany; and the University of Notre Dame in Notre Dame, Indiana, US, have published their paper on the 3D magnetic logic gate in a recent issue of Nanotechnology.

"We showed for the first time that magnetic field coupling can be exploited in all three dimensions in order to realize magnetic logic computing circuitry, and therefore paves the way for new technologies, where high integration densities combined with low power consumption can be achieved," Eichwald told

The 3D magnetic logic gate consists of three input magnets that influence the magnetic state of one output magnet. To prepare the output magnet, the researchers used a focused ion beam to irradiate a 40 x 40-nm area of the magnet to destroy its crystalline structure, creating a domain wall. When the magnetic fields from the three input magnets are placed within 100 nm of the irradiated spot, the domain wall's magnetic state can be controlled. As a result, the output magnet can be switched between the "0" and "1" states.

SEM image of the 3D magnetic logic gate. The input magnet I3 is located in a different layer than the rest of the magnets, making the gate three-dimensional. Credit: Eichwald, et al. ©2014 IOP

One important feature of the 3D magnetic logic gate is that one of the input magnets is arranged in an extra layer in comparison to 2D gates. Adding a third dimension enhances the amount of magnetic area surrounding the output magnet by 1/3, and also increases the influence of each input magnet by 1/6. These stronger magnetic effects reduce the error rate and improve the functionality of the gate. The input magnet in the third dimension also programs the gate to operate as either a NOR or NAND gate.

NML has several potential advantages compared to transistors. One is that there is no need for electrical wiring or interconnects because the computation is performed entirely by magnetic interactions between neighboring magnets. NML also operates with , which in turn enables the combination of logic and memory functionality in a single device.

There is also the advantage of high densities using NML, which is possible in part due to the small size of the 3D magnetic gates (here, about 700 x 550 nm). Although high densities lead to the problem of stray magnetic fields interfering with magnets other than their nearest neighbors, the researchers note that previous research has already begun discussing and proposing solutions to these problems. Overall, NML could have a variety of applications.

"The main aspect of 3D nanomagnetic logic is that you can build up circuits, in which a huge number of the computing processes is done simultaneously (the keyword is systolic architecture), while the is kept at a minimum (as you only need to generate a global magnetic field and then you can clock the whole circuitry)," Eichwald said. "Applications are digital filtering, decoding and cryptography. Here all computing processes should be done by magnets."

The results here pave the way for the development of other 3D architectures of NML circuits in the future.

"The future research plans are to investigate a 3D full adder structure, with the lowest possible number of magnets and the smallest area consumption," Eichwald said.

Explore further: Researchers build switchable magnetic logic gate

More information: Irina Eichwald, et al. "Majority logic gate for 3D magnetic computing." Nanotechnology 25 (2014) 335202 (8pp). DOI: 10.1088/0957-4484/25/33/335202

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Aug 08, 2014
This comment has been removed by a moderator.
5 / 5 (1) Aug 08, 2014
While I can understand this could be made into a functional ic chip, my question is how can you get the data and signals into and back out of the chip? Hall effect maybe on the output? I have no idea how they would get data into it though unless it had tiny electric coils or something on the inputs. Wouldn't the only power consumption of the chip be on the inputs and output circuits since the magnetic insides would switch due to magnetic fields? Of course the actual paper is behind a paywall.......
3 / 5 (3) Aug 08, 2014
The advantage here is that the states don't need a refresh.
(which could also be a disadvantage in security related applications...but that's just a tiny niggle)

Input would probably be via induction. Output can be via a number of effects (e.g. magnetooptic readout - which is what they used in the paper)

Of course the actual paper is behind a paywall.

If you're interested pay it. It's only 33 bucks.
Whydening Gyre
4 / 5 (4) Aug 08, 2014
The_Magnetic_field_of_the_Electric_current: https://www.acade..._current

Yeah but, George....
What if it's actually - the_Electric_Current_of_the_Magnetic_Field?
Whydening Gyre
1 / 5 (1) Aug 08, 2014
The advantage here is that the states don't need a refresh.
(which could also be a disadvantage in security related applications...but that's just a tiny niggle)

Input would probably be via induction. Output can be via a number of effects (e.g. magnetooptic readout - which is what they used in the paper)

Didn't I just read another Physorg article referencing control of magnetic fields with light?
Whydening Gyre
3 / 5 (2) Aug 08, 2014
Here it is.
Of course - George R. super spammed it, so many may not have read it because of that....
3 / 5 (2) Aug 09, 2014
ReRAM already uses a fraction of the cell architecture as NML & also does not need "refresh" as do NAND & DRAM cell architecture which are presently the two most popular memory chipsets. With ReRAM using 10 nanometer cell architecture, it already beats 15nm NAND or DRAM at 16-20nm both of which require energy consuming refresh.

Looking at the amount of real estate required for NML at about 750nm, that's 75 times more than for the new ReRAM chipsets & ReRAM can be fabricated into 3D as Crossbar plans to do & there are no problems with crossover inductance as with NML. Additionally, ReRAM cell architecture has not reached the smallest capable limits, it can probably go as low as 5nm within a few of years with comparable low power consumption as NML. If NML has a future, it is a long way down the road by many years, its only chief advantage appears that it may be cheaper to produce due simpler architecture design compared to other memory chipsets.

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