Spin-valve planar Hall sensor for single bead detection

✍ Scribed by Tran Quang Hung; Sunjong Oh; Jong-Ryul Jeong; CheolGi Kim

• Book ID: 104092681
• Publisher: Elsevier Science
• Year: 2010
• Tongue: English
• Weight: 583 KB
• Volume: 157
• Category: Article
• ISSN: 0924-4247
• DOI: 10.1016/j.sna.2009.11.033

✦ Synopsis

The planar Hall effect (PHE) sensor with a junction size of 3 m × 3 m for a single micro-bead detection has been fabricated successfully using a typical spin-valve thin film Ta(5)/NiFe(16)/Cu(1.2)/NiFe(2)/IrMn(15)/Ta(5) nm. The PHE sensor exhibits a sensitivity of about 7.2 V Oe -1 in the magnetic field range of ±7 Oe approximately. We have performed an experiment to illustrated the possibility of single micro-bead detection by using a PHE sensor. A single micro-bead of 2.8 m diameter size is secluded from 0.1% dilute solution of the Dynabeads ® M-280 dropped on the sensor surface and is located on the sensor junction by using a micro magnetic needle. The comparison of the PHE voltage profiles in the field range from 0 to 20 Oe in the absence and presence of a single micro-bead identifies a single Dynabeads ® M-280, the maximal signal change as large as V ∼ 1.1 V can be obtained at the field ∼6.6 Oe. The results are well described in terms of the reversal of a basic single domain structure.