Spin polarization decay in magnetic tunnel junctions with semimetal-inserted layers

Title
Spin polarization decay in magnetic tunnel junctions with semimetal-inserted layers
Authors
이경일노종욱이기영장준연신경호Mark Johnson이우영
Keywords
magnetic tunnel junctions; TMR; Spin polarization decay
Issue Date
2010-05
Publisher
Journal of applied physics
Citation
VOL 107, NO 9, 093913-1-093913-4
Abstract
Magnetic tunnel junctions (MTJs) were fabricated with a thin layer of semimetallic bismuth inserted between the tunnel barrier and the top ferromagnetic electrode. The tunneling magnetoresistance (TMR) was measured on a set of samples for which the thickness of the inserted layer varied from 0 to 20 nm. The TMR decreased with an exponential decay length that was found to be ΛBi = 4.1 nm = 0.48 λF,Bi, where λF,Bi is the Fermi wavelength measured in comparable Bi films. This result is in remarkably good agreement with the decay length previously measured in MTJs with inserted copper layers, λCu = 0.58 λF,Cu, even though the values of λF differ by an order of magnitude. It thereby gives a confirmation that the characteristic length scale of the tunneling density of states is the Fermi wavelength. Measurements of TMR as a function of bias voltage show a large asymmetry and the peak TMR is shifted to a nonzero value.
URI
http://pubs.kist.re.kr/handle/201004/38222
ISSN
0021-8979
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