A physics professor from the University of California, Santa Cruz and a scientist at Hitachi Global Storage Technologies have reported in a scientific journal that spinning magnetic fields can cause “avalanche” effects/ripples across the surface of disks, resulting in a loss of data on the disk drive. 

The two scientists speculate that when a disk read/write head is above an area of a disk and writes to it with a one or zero the magnetic polarity of the atoms in the bit underneath the head is altered. This polarity is a spinning direction of the atoms. Each atom “wobbles” as it spins, similar to the way the Earth rotates on its axis, a phenomenon known as precession. 

As the atoms undergo spin precession they are stopped by other atoms going in another spin direction, but while they are wobbling they exert sufficient force on nearby atoms to also change their spin direction. This creates an avalanche type of spin precession that happens before it is in contact with the magnetic recording material due to an increase in the distance from the write head.

The scientists also postulate that recording material with a better-formulated chemistry could increase the damping effect and reduce or stop the spin precession avalanche effect; which in turn would reduce disk drive data loss from the effect.

While the data loss isn’t a widely occurring thing the probability of it happening increases as disk drive capacity increases, meaning a greater areal density, and more closely-packed and smaller magnetic areas (bits) on the surface of the disk.

By measuring the damping ability of materials for the magnetic recording layer, as well as their other magnetic properties, the scientists hope to make changes to the recording layer chemistry that will create more reliable disk drives.