Practice question · Multiple choice
A hard drive stores bits as magnetic domains, and shrinking them indefinitely fails. What sets the floor?
Hints
- Ask what competes with the energy holding a magnetic domain in place at room temperature.
- A bit that flips by itself is a bit that has forgotten. What supplied the energy?
Show the answer
D. Thermal stability, below which a domain flips on its own
Why
Below the superparamagnetic limit, kT at room temperature is comparable to the barrier holding the domain, so bits flip at random. Physics rather than engineering sets the density ceiling, which is why perpendicular recording and heat-assisted media were developed to raise the barrier instead.
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