Nanodevices and Nanostructures
Magnetic Tunnel Junction Nanosensors
MgO based magnetic tunnel junction (MTJ) stacks exhibiting large tunneling magnetoresistance (TMR) and a low resistance-area product (RxA) stand out as the best starting point for nanometric sensing devices. In collaboration with INL we developed nanoscale MTJ sensors with stack incorporated bias which yielded top sensitivities reported for nanometric devices. Furthermore, these values of are very competitive with those reported for single micrometric spin-valve sensors without adding flux-guides or permanent magnets. Our design has thus the major advantage of having a high spatial resolution allied to a linear operation range (and thus sensitivity) controlled by the biased sensing layer.
Nanotechnology 27 (2016) 045501
IEEE Transactions on Magnetics, 50 (2014)
JAP 115 (2014) 17E526
Spin Valve Nanosensors
When combined with magnetic flux concentrators, spin valve sensors may provide the desired features for room temperature detection of low magnetic fields within the sub-nanoTesla range. To fulfill such requirements os high spatial resolution one solution relies on the miniaturization of the GMR sensors down to sub-micrometric or nanometric scale dimensions, depending on the desired resolution. However, a reduction in the sensor size leads to a significant increase in the demagnetizing effects which leads to a decrease in sensitivity. Strategies focusing either on the materials side or by employing external elements are developed towards significant gains in sensitivity recovering in part the loss due to shrinking size.
Sensors 15 (2015) 30311
IEEE Transactions on Magnetics 50 (2014) 4401604
Simulations of Nanodevices
Decisions concerning mask layout and design rules are assisted by micromagnetic and magnetotransport simulations. The simulation tool is able to account for a complex state of the art tunnel junctions stack (e.g. bottom-lead / seed-layer / antiferromagnet / pinned-layer / spacer / reference-layer / barrier / free-layer / cap / top-lead) and include all magnetic interactions present in such a sample, approximating the simulated case to a practical device, and thus provide deeper insight into the overall device response, therefore yielding design rules over the nanoprocess.
Nanotechnology 27 (2016) 045501
Physica B 435 (2014) 163
IEEE Transactions on Magnetics 49 (2013) 4405