Effect of thermal annealing on Boron diffusion, micro-structural, electrical and magnetic properties of laser ablated CoFeB thin films

Abstract

We report on Boron diffusion and subsequent crystallization of Co40Fe40B20 (CoFeB) thin films on SiO2/Si(001) substrate using pulsed laser deposition. Secondary ion mass spectroscopy reveals Boron diffusion at the interface in both amorphous and crystalline phase of CoFeB. High-resolution transmission electron microscopy reveals a small fraction of nano-crystallites embedded in the amorphous matrix of CoFeB. However, annealing at 400°C results in crystallization of CoFe with bcc structure along (110) orientation. As-deposited films are non-metallic in nature with the coercivity (Hc) of 5Oe while the films annealed at 400°C are metallic with a Hc of 135Oe

Anisotropic magnetoresistance of individual CoFeB and Ni nanotubes with values of up to 1.4% at room temperature

“…4(b)] have been reported for many amorphous and granular alloys with intermediate resistivities 44,45 including CoFeB. 46,47 The following dependencies have been discussed for the low-temperature R when considering Coulomb interaction in disordered systems: exp( √ T 0 /T ), 48 a power law 1/T α or ln (T 0 /T) 38 (T 0 is a characteristic temperature and 0 < α 1). The first (latter) occurs for systems with high (intermediate) resistivity.…”

Resistance minimum and electrical conduction mechanism in polycrystalline CoFeB thin films

“…Therefore, a basic understanding of the electrical and magneto-transport properties of CoFeB thin films prepared under different conditions is essential for further improvement of any device based on this ferromagnetic alloy. Still there are only few reports on the electrical transport properties of CoFeB thin films including composites and nanotubes [7][8][9][10][11][12][13]. The electrical resistivity ρ(T) of a crystalline film is significantly lower as compared to that of an amorphous film [11,12].…”

“…Still there are only few reports on the electrical transport properties of CoFeB thin films including composites and nanotubes [7][8][9][10][11][12][13]. The electrical resistivity ρ(T) of a crystalline film is significantly lower as compared to that of an amorphous film [11,12]. While the crystalline films show a metallic behaviour, negative temperature coefficient of resistance has been reported for the amorphous or composite films [8,12].…”

“…The electrical resistivity ρ(T) of a crystalline film is significantly lower as compared to that of an amorphous film [11,12]. While the crystalline films show a metallic behaviour, negative temperature coefficient of resistance has been reported for the amorphous or composite films [8,12]. Thus, the crystalline quality plays an important role in the process of electrical conduction of these films.…”

Effect of stoichiometry of Fe and Co on the temperature stability of the magnetic anisotropy in Pr-Dy-Fe-Co-B alloys

“…However, there are no available data on studies of the role of boron diffu sion in systems, such as (Pr,Dy) x -(Fe x CO 1 -x )-B, although anomalous diffusion mobility of boron in FeCoB alloys used in spintronics is reliably known [6,7]. According to available data [1], it can be expected that high cobalt concentrations in our series of sam ples will favor the presence of additional phases with high boron concentration in the sample.…”