ISSN:
1662-0356
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Natural Sciences in General
,
Technology
Notes:
Co-Fe-B/MgO/Co-Fe-B magnetic tunnel junctions were fabricated using UHV magnetronsputtering. Magnetoresistance and spin-transfer switching properties were investigated as a functionof Co-Fe-B free layer thickness, between 1.5 nm and 3 nm. The intrinsic switching current andthe thermal stability were derived from the pulse duration dependence of the switching current,analyzed based on the thermally activated switching model. Both switching currents, correspondingto parallel (P) to antiparallel (AP) (Ic0+) and AP to P (Ic0–) magnetization reversal, were foundto be roughly proportional to the free layer thickness. The averaged intrinsic switching currentdensity Jc0av = (Ic0+–Ic0–)/(2A) (where A is the cell area) was in the range of 1–2×107 A/cm2. Theexperimental values of Jc0±agreed with theoretical values, determined taking into account the spintransferefficiency for the case of magnetic tunnel junction. The thermal stability of the P and APstates was different, but roughly proportional to the free layer thickness in both cases. We attributethis difference to a disparity in the net magnetic field acting on the free layer magnetization in the Pand AP states. The average of the thermal stability in the two states varied from 30 to 60 when thefree layer thickness was increased. According to our findings, to guarantee the non-volatility of anMRAM device for about 10 years, the Co-Fe-B free layer should be thicker than 2 nm
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/01/42/transtech_doi~10.4028%252Fwww.scientific.net%252FAST.45.2633.pdf
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