Magnetics Business & Technology - March/April 2023 - 16

RESEARCH & DEVELOPMENT
A Magnetic Nano-Elevator for Three Dimensional Spintronic Devices
Figure 1. A nano-elevator of magnetic information for the connection of spintronic planes.
Information technologies will be responsible for about 20%
of electricity consumption worldwide by 2025, which urgently
requires the development of new types of greener nanoelectronic
devices. Spintronics, making use of not only the charge of
electrons but also of its intrinsic angular momentum (its spin) is
an emerging technology that can overcome some of these challenges,
thanks to its non-volatility character, full compatibility with
CMOS (complementary metal-oxide-semiconductor), low and fast
write/reading processes, and high endurance.
However, as nanoelectronic devices move towards denser forms
exploiting three dimensions, new mechanisms to efficiently
interconnect functional planes become necessary. The shift to 3D
devices should enable ultra-highly dense storage and memory
devices, but their realization brings huge challenges, from their
fabrication to their interconnection or effective heat dissipation.
In a work recently published in ACS Nano, an international team
led by Luka Skoric (from the Cavendish Laboratory of the University
of Cambridge in UK), and Amalio Fernández-Pacheco (from
the Institute of Nanoscience & Materials of Aragon in Spain),
propose and demonstrate for the first time a new concept for the
transfer of magnetic data in three dimensions based on geometrical
effects for the interconnection of functional spintronic planes.
Unlike traditional spintronic devices which use pulses of current to
move magnetic bits, this mechanism exploits instead large thickness
gradients, which promote the spontaneous motion of bits
without the need to apply any external stimuli. The magnetic data
in these devices are encoded as domain walls that " auto-move "
without external stimuli along nanowires with spiral shape.
" This work proposes and demonstrates for the first time a new
concept for the transfer of magnetic data in three dimensions
based on geometrical effects " says Luka Skoric from the University
of Cambridge and lead author of the publication. " Until now,
the motion of magnetic bits in spintronic devices such as the racetrack
memory has been typically based on applying external in16
Magnetics Business & Technology * March/April 2023
puts, typically electrical current pulses. The scalability of racetrack
devices to three dimensions is very appealing for future technologies,
but brings great challenges regarding their fabrication and
heat dissipation during operation. The automotion of domain walls
across the devices demonstrated here is a robust and flexible way
to move bits in 3D " .
You can think about this effect as a " magnetic nano-elevator
which transmits information between spintronic planes " says
Amalio Fernández-Pacheco, senior lead author of the publication.
" Once the domain walls are introduced into the 3D nanowire
devices, they move by themselves without the need to apply any
external input as normally required, namely magnetic fields, voltages
or electrical currents. The geometry of the devices does it
all. "
The devices were fabricated
at the University of Cambridge
by a combination of state-ofthe
art nanoscale 3D printing
and thermal evaporation, and
consist of 3D spiral structures
of several microns in length
and a few tens of nanometre
in width and thickness. After
their fabrication, they were
investigated at the ALBA Synchrotron
and the Synchrotron
SOLEIL (France), where X-ray
microscopy techniques were
employed to directly observe
the automotion of domain
Amalio Fernández-Pacheco (from
the Institute of Nanoscience &
Materials of Aragon in Spain) and
Luka Skoric (from the Cavendish
Laboratory of the University of
Cambridge in UK)
walls. Experimental studies were complemented by employing
micromagnetic simulations developed at the University of Vienna.
The automotion of domain walls had been previously observed in
planar spintronic devices due to several mechanisms, from curwww.MagneticsMag.com
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Magnetics Business & Technology - March/April 2023

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