Nanowires of Fe/multi-walled carbon nanotubes and nanometric thin films of Fe/MgO

Abstract

We observed that nanowires of Fe grown in the lumens of multi-walled carbon nanotubes required four times higher magnetic field strength to reach saturation compared to planar nanometric thin films of Fe on MgO(100). Nanowires of Fe and nanometric thin films of Fe both exhibited two fold magnetic symmetries. Structural and magnetic properties of 1-dimensional nanowires and 2-dimensional nanometric films were studied by several magnetometery techniques. The θ-2θ x-ray diffraction measurements showed that a (200) peak of Fe appeared on thin film samples deposited at higher substrate temperatures. In these samples prepared at higher temperatures, lower coercive field and highly pronounced two-fold magnetic symmetry were observed. Our results show that maximum magnetocrystalline anisotropy occurred for sample deposited at 100 °C and it decreased at higher deposition temperatures.

Electromagnetic Radiation Effects on MgO-Based Magnetic Tunnel Junctions: A Review

“…The phenomenon of tunnel magnetoresistance (TMR) has gained enormous attention in recent decades because of its essential applications in nonvolatile magnetoresistive random-access memory (RAM) and next-generation magnetic field sensors [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 ]. This interest follows the emergence and success of related magnetoresistance, such as anisotropic magnetoresistance (AMR) and giant magnetoresistance (GMR).…”

“…2 "4 for Co60 radiation in lead and water.Experimental results of plane parallel Cs 137 , Co60 , and Na 24 gamma radiation diffusing through iron are com-Transmission of gamma radiation through iron. A, Cs 137 radiation of 0.66 Mev; •, Co 60 radiation of 1.17 and 1.33 Mev; •, Na 24 radiation of 1.38 and 2.76 Mev.…”

Nanowires of Fe/MgO/Fe Encapsulated in Carbon Nanotubes

“…The symmetry of electronic wave functions plays a paramount role in coherent spin-polarized tunneling, which gives rise to enormous TMR effects. Shape anisotropy plays an important role in coherent spin-polarized tunneling of electrons across the insulator barrier; thus, switching the geometry of TMR from planar films to nanowires will increase the coherence thus increasing the MR ratio [8,9]. The importance of shape anisotropy in ferromagnet/insulator/ferromagnet trilayer structures in particular for Fe/ MgO/Fe and the effect of encapsulation of a TMR by carbon tubes are discussed in this chapter based mainly on magnetic measurement results and subsequent interpretations.…”