Summary: Journal of Magnetism and Magnetic Materials 310 (2007) e992e993
Detection of a single magnetic dot using a Planar Hall sensor
K.M. Chuia,Ã, A.O. Adeyeyea
, Mo-Huang Lib
Information Storage Materials Laboratory, Department of Electrical and Computer Engineering, National University of Singapore, 117576, Singapore
Institute of Bioengineering and Nanotechnology, 31 Biopolis Way, The Nanos, #04-01, 138669, Singapore
Available online 21 November 2006
We have successfully demonstrated the detection of pseudo-magnetic beads placed on top of 4 Â 4 mm2
and 5 Â 5 mm2
trilayer (Si/Co10 nm /Cu2 nm /NiFe10 nm) sensors. The sensor and the pseudo-magnetic beads were fabricated using a combination of e-
beam and optical lithography techniques. Magneto-transport measurements detect the presence of dots placed on top of the PHE
junction, even to the limit of single-dot. We observed that the PHE response is very sensitive to changes in the density of coverage of the
sensing area with pseudo-magnetic beads. We attribute this effect to the direct coupling between the dots and the sensing layer below.
r 2006 Elsevier B.V. All rights reserved.
PACS: 75.70.Ài; 85.70.Àw
Keywords: Planar Hall effect; Magnetic biosensors; Magnetic beads; Single micro-bead detection