Current-Driven Domain Wall Dynamics in Magnetic …
135
1 Role of spin Hall effect from capping and seed layers to stimulate the exchange coupling torques
M U /M L ratio. It is remarkable to note that the DW velocities in more compensated
wires are observed up to 750 m/s. The DWs move much faster as the ratio of M U /M L
approaches to 1. Moreover, the 1D model for the SAF structures predicts the DW
velocity more than 1000 m/s in fully compensated wires [86].
4.3 Determination of Data Retention in Synthetic
Antiferromagnetic Devices
In the DW based memory devices, the digital data ‘0 and ‘1’ are stored in the form of
magnetic domains within ferromagnetic wires. However, the magnetic domains have
a finite probability to overcome the energy barrier (E G ) between the ‘0 and ‘1’ states
due to thermal excitations. The switching probability of the data bits between the
two states due to the thermal fluctuation can be calculated using Boltzmann factor
as below[93–95]:
P ∝ exp
−E G
k B T
,
(21)
135
1 Role of spin Hall effect from capping and seed layers to stimulate the exchange coupling torques
M U /M L ratio. It is remarkable to note that the DW velocities in more compensated
wires are observed up to 750 m/s. The DWs move much faster as the ratio of M U /M L
approaches to 1. Moreover, the 1D model for the SAF structures predicts the DW
velocity more than 1000 m/s in fully compensated wires [86].
4.3 Determination of Data Retention in Synthetic
Antiferromagnetic Devices
In the DW based memory devices, the digital data ‘0 and ‘1’ are stored in the form of
magnetic domains within ferromagnetic wires. However, the magnetic domains have
a finite probability to overcome the energy barrier (E G ) between the ‘0 and ‘1’ states
due to thermal excitations. The switching probability of the data bits between the
two states due to the thermal fluctuation can be calculated using Boltzmann factor
as below[93–95]:
P ∝ exp
−E G
k B T
,
(21)