Home

About

Advanced Search

Browse by Discipline

Scientific Societies

E-print Alerts

Add E-prints

E-print Network
FAQHELPSITE MAPCONTACT US


  Advanced Search  

 
Magnetic and tunneling magnetoresistive properties of an all-oxide Fe3O4-Al2O3 granular system D. Tripathy and A. O. Adeyeye*
 

Summary: Magnetic and tunneling magnetoresistive properties of an all-oxide Fe3O4-Al2O3 granular system
D. Tripathy and A. O. Adeyeye*
Information Storage Materials Laboratory, Department of Electrical and Computer Engineering,
National University of Singapore, Singapore 117576
S. Shannigrahi
Institute of Materials Research and Engineering, 3 Research Link, Singapore 117602
Received 3 June 2007; revised manuscript received 23 August 2007; published 16 November 2007
A systematic study on the structural, magnetic, and transport properties of an all-oxide granular system
consisting of Fe3O4 grains dispersed in an insulating Al2O3 matrix is presented. X-ray diffraction and trans-
mission electron microscopy analyses provide the structure of nanosized Fe3O4 grains embedded in an amor-
phous Al2O3 matrix and confirm that the Fe3O4 grain size decreases with increasing Al2O3 volume fraction x.
Magnetic measurements further show that the coercivity of the granular films decreases with increasing x due
to decreasing Fe3O4 grain size, with the magnetization curves exhibiting typical superparamagnetic character-
istics for x 0.19. Temperature dependence of resistance and nonlinearity in current-voltage characteristics
confirms that the spin dependent tunneling of conduction electrons across grains dominates the transport
properties. This tunneling conductance depends on the relative orientation of magnetization between Fe3O4
grains, which results in an isotropic granular tunneling magnetoresistance TMR effect. We also observed that
the granular TMR ratio has strong temperature dependence and decreases with increasing temperature for all
the granular films.
DOI: 10.1103/PhysRevB.76.174429 PACS number s : 75.47.De, 72.25. b, 73.40.Gk, 74.25.Ha

  

Source: Adeyeye, Adekunle - Department of Electrical and Computer Engineering, National University of Singapore

 

Collections: Physics; Materials Science