The way you write to your hard drive and to
this MRAM is that you expose it to a magnetic
field. However, it is NOT the overall strength
of the magnet that matters. What does matter is
the amount of magnetic flux which passes through
the medium you are writing to. You can increase
flux by either increasing the strength of the
magnet used to write, or by shrinking the gap
between the two poles.
Your hard drive uses a write head with an
extremely small gap, and when put close to the
magnetic medium produces alot of flux. But
because the overall magnetic field strength is
small and the force falls off(I want to say as the
square of the distance but I am not sure because
I don't want to treat it as a point source) very
quickly as you move away. That is why you don't
have to shield platters from each other in your
hard drive.
Back to MRAM. This is why you don't need to
shield the MRAM either, because even if you go
at it with a pretty good magnet you will not get
enough flux through the magnetic film to change
the direction of the field stored.
Yes, there would probably be enough energy in
an EMP pulse to take this out. But it would have
already fried all the semi-conductors on the
motherboard. So either way your just sitting in
the dark.
Slashdot Mirror
The way you write to your hard drive and to
this MRAM is that you expose it to a magnetic
field. However, it is NOT the overall strength
of the magnet that matters. What does matter is
the amount of magnetic flux which passes through
the medium you are writing to. You can increase
flux by either increasing the strength of the
magnet used to write, or by shrinking the gap
between the two poles.
Your hard drive uses a write head with an
extremely small gap, and when put close to the
magnetic medium produces alot of flux. But
because the overall magnetic field strength is
small and the force falls off(I want to say as the
square of the distance but I am not sure because
I don't want to treat it as a point source) very
quickly as you move away. That is why you don't
have to shield platters from each other in your
hard drive.
Back to MRAM. This is why you don't need to
shield the MRAM either, because even if you go
at it with a pretty good magnet you will not get
enough flux through the magnetic film to change
the direction of the field stored.
Yes, there would probably be enough energy in
an EMP pulse to take this out. But it would have
already fried all the semi-conductors on the
motherboard. So either way your just sitting in
the dark.