“Magnetic Nanodots Simulation using OOMMF”

Aim

Micro-magnetic simulation to study the magnetic behavior of magnetic nano dot array with varying aspect ratio ( L/D). For magnetic nano-dot array fabricated using self-ordered porous ultra-thin alumina template.

Importance:

• Currently in terms of performance, speed Processor outperforms memory to great extent. The research permits to fulfill the Kryder's law, it is the storage equivalent of Moore's Law.
• Micro-magnetic Simulations showed Vortex core switching speed < 50ps,
• Tbit/in² recording density can be achieved magnetic nanodot array using self-ordered porous ultrathin alumina template.
• Ultra-small magnetic field sensors.

Conclusions from primary simulations:

• Almost all vortex present at 0 T, means vortex stable at ambient condition.
• For annihilation of vortex 30 mT to 100 mT change will be required.
• Nucleation and annihilation of vortex is perpendicular to applied field.
• Around “easy axis changeover field” there are two vortex present in-plane and out of plan vortex.
  • Nucleation and annihilation of in-planes happens first and then out of plane.
• The chirality of vortex is not correlated
  • Hx it is unpredictable
  • Hz is slightly predictable for higher thickness.
• For Hx – formation of vortex is delayed as we come from 1.5 mT to -1.5 mT.
  • Required field goes negative to positive as we increase thickness from 10 nm to 100 nm.
  • For Hz it is vice versa.
• As length of dot increases the number of vortex also increases which can be used to increase recording density further (like bubbled logic).
• After around 40 nm thickness the vortex (at 100^th and 300^th iteration) have different nature- present at top and bottom differently, represented by clockwise and anti clockwise direction in the table and no vortex like structure at middle.
• For 7 dot array system diameter with 30nm diameter is completely uncorrelated with no relation can not predict anything.
• For 70nm diameter the dots mostly followed a way to get magnetize (bottom two first, then middle and top) but magnetization still remains uncorrelated.