From Magnetic Nanoparticles to Magnetoresistive Biosensors

I. Ennena, C. Albonb, A. Weddemannc, A. Augeb, P. Hedwigb, F. Wittbrachtb, A. Regtmeierb, D. Akemeierb, A. Dreyerd, M. Petere, P. Jutzid, J. Mattaye, N. Mitzelf, N. Millb and A. Hüttenb aInstitute of Solid State Physics, Vienna University of Technology, A-1040 Vienna, Austria bDepartment of Physics, Thin Films and Physics of Nanostructures, Bielefeld University, 33615 Bielefeld, Germany cMassachusetts Institute of Technology, RLE, LEES, 77 Massachusetts Ave, 02139 Cambridge, MA, USA dDepartment of Chemistry, Organometallic Chemistry, Bielefeld University, 33615 Bielefeld, Germany eDepartment of Chemistry, Organic Chemistry I, Bielefeld University, 33615 Bielefeld, Germany fDepartment of Chemistry, Inorganic and Structural Chemistry, Bielefeld University, 33615 Bielefeld, German y

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This paper highlights recent advances in synthesis and magnetotransport properties of magnetic Co nanoparticles. It is shown that magnetic Co nanoparticles self-assembled in nanoparticular monolayers revealing giant magnetoresistance similar to granular systems but with additional features resulting from dipolar interactions between small domains of nanoparticles. A spin-valve with one magnetic Co nanoparticular electrode is employed as a model to demonstrate that individual magnetic moments of Co nanoparticles can be coupled to a magnetic Co layer which in turn offers tailoring of the resulting giant magnetoresistance characteristics. In addition, it is demonstrated that combining a magnetic on-off ratchet with magnetic tunneling junctions integrated in the ratchet introduces a new biosensor concept enabling: (1) simultaneous transporting and separating biomolecules, (2) dynamical biomolecule detection when passing magnetic tunneling junctions in a 1D arrangement. It is projected that this biosensor concept could be applied for viruses as well as for bacteria.

DOI: 10.12693/APhysPolA.121.420 PACS numbers: 85.70.-w, 85.75.-d, 75.75.Fk, 64.75.Yz, 87.85.fk