TOPICS OF DISCUSSION
What is SPINTRONICS?
•Spintronics is a new branch of electronics in
which electron spin, in addition to charge, is
manipulated to yield a desired electronic
outcome. The spin itself is manifested as a
detectable weak magnetic energy state
characterized as “spin up” or “spin down”.
•Conventional electronic devices rely on the
transport of electrical charge carriers –
electrons in a semiconductor such as silicon.
• Devices that rely on the
electron’s spin to
perform their functions
form the foundations of
electronics), also known
as magneto electronics.
• Spintronics devices are
smaller than 100 nm in
size, more versatile and
more robust than those
making up silicon chips
and circuit elements.
• Spintronics burst on the scene in 1988 when
French and German physicists discovered a
very powerful effect called Giant
• It results from subtle electron-spin effects in
ultra thin multilayers of magnetic materials,
which cause huge changes in their electrical
resistance when a magnetic field is applied.
This resulted in the first spintronic device in
the form of the spin valve.
• SPINTRONICS,short for spin
electronics,is the study of
electron spin in materials in
order to better understand its
behavior,with the hope of
developing an entirely new
generation of microelectronic
• An electron is just like
a spinning sphere of
• The electron has a
spin,that makes it
behave almost as if it
were a magnet twirling
about the axis
connecting its north
poles.Electron can have
spins oriented in
• A magnetic field causes an electron to
swivel like a needle of a compass to line
up with the field(left).But the spin axis
precesses like a wobbling top(right).
• When the magnetic field is removed,the
electron stops precessing and locks the
orientation of its spin.
• The spin of the electron has three states
to it; up, down, and in between.
• In today’s world of computers the spin
is ignored and you have either on/off,
0/1, or up/down but with the spin of the
electron you can have many states and
not be limited with those two states.
• Because of these many states
information can be processed a whole
lot faster if an electrons spin carries
• Miniaturization has always been a part of rapidly
developing electronic industry. But there is a limit to the
number of transistor or other electronic component that
can be cramped on a single chip
• . Besides this, small electronic devices are plagued by a
big problem of energy loss or dissipation, as signals
pass from one transistor to the next transistor. So the
only solution to overcome this problem is to find some
method that takes both the problem into account.
• Apart from miniaturization another problem with
devices is that their working is based on use of
electronic charges. This working has several
disadvantages; power failure being one of them. In case
of a power cut, information stored by electronic charges
is lost. Hence, before a computer is turned off, all the
work is saved on the hard disk.
• `Spintronics` or Spin electronics, is one
of the solutions to overcome this
• These Spintronic devices will work in
(1) Information will be stored (written)
into spins as a particular spin
orientation (up or down)
(2) The spins, being attached to mobile
electrons, will carry the information
along a wire
(3) The information will be read at a
• The spintronic devices have opened us
to a whole new network of high –tech
• Some of these devices are:
• MAGNETIC RANDOM ACCESS
• MAGNETIC TUNNEL JUNCTION
Resistance: R↑ ↓
Consists of two layers of
magnetic metal, such as
cobalt-iron, separated by an
ultra thin layer of insulator,
typically aluminum oxide with
a thickness of about 1 nm.
The insulating layer is so thin
that electrons can tunnel
through the barrier if a
avoltage is applied between
the two metal electrodes.
The current depends on the
magnetizations of the two
ferromagnetic layers, which
can be changed by an applied
tunneling magneto resistance
• MRAM stands for
Magnetic Tunnel Junctions
• It places the
on the surface of
a silicon chip and
• Just like a hard
stored in the
magnetic domains is
non volatile.It is not
lost when the power
• The two main
concept that govern
– Giant Magnetoresistance
– The Tunneling Magneto
• A Transpinnor is a bridge of four
electrically connected GMR films whose
resistance is controlled by the magnetic
field from the current in one of more
input strip lines electrically isolated from
• Transpinnors can be used as selection
matrix elements for magnetic
memories,for logic elements of all
kinds(e.g..AND,OR,NAND , NOT),for
• The various advantages of spintronics is
• Does not require unique and specialized
semiconductors;can be implemented
with common metals such as Cu,Al.
• Spintronic devices consume less power.
• The memory remains non-volatile.
• The various disadvantages are as
• The fringe fields generated interfere
with the neighboring elements.
• Hazards of holes
• Much remains to be understood about
the behavior of electron spins in
materials for technological applications
• Spintronics is a rapidly emerging field of
science and technology that will most
likely have a significant impact on the
future of all aspects of electronics as we
continue to move into the 21st century.
electronics are based
on the charge of the
electron. Attempts to
electron, its spin,
have given rise to a
new, rapidly evolving