Electron-beam evaporated cobalt films on molecular beam epitaxy prepared GaAs(001)

Ding, Zhao; Thibado, P. M.; Awo-Affouda, C.; LaBella, V. P.

doi:10.1116/1.1771674

Cited by 14 publications

(8 citation statements)

References 22 publications

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“…Nevertheless, the experimentally stabilized BCC cobalt thin films [20] were explained to originate from such imperfections or substrate lattice constant mismatch at an early stage of growth. Furthermore a critical thickness above which the BCC phase begins to transform to HCP one was identified [27]. In HCP-cobalt, our c/a ratio (1.603) and magnetic moment (1.634 µ B ) are in good agreement with experiments [18][19][20][21] and in better agreement than recent full potential calculations [25].…”

Section: Resultssupporting

confidence: 84%

Ab initiostudies of magnetic properties of cobalt and tetracobalt nitrideCo4N

2007

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Magnetic properties and bonding analyses of perovskite structure Co4N nitride have been investigated within density functional theory using both pseudo potential and all electron methods. In the same time, the structural and magnetic stability of pure cobalt in hexagonal close packed (HCP), face centered cubic (FCC) and body centered cubic (BCC) structures are reviewed. At equilibrium, non-spin polarized (NSP) and spin polarized (SP) calculations of the energy versus volume show that the ground state is ferromagnetic in both materials. HCP-Co is found to be more stable than the cubic ones. Magnetic moments of Co atoms in Co4N nitride respectively belonging to two different crystallographic sites are studied over a wide range of the cubic lattice constant, and a comparison with the FCC-cobalt one is given. The volume expansion in the nitride indicates that the corner Co I atoms show localized magnetism while face center Co II atoms exhibit an itinerant behavior. Like in FCC-Fe/Fe4N, a "low volume-low moment" and "large volume-high moment" behavior is observed for FCC-Co/Co4N. The density of states of the Co4N ferromagnetic ground state is interpreted within the rigid band model. The different bonding characters of Co I -N versus Co II -N are shown with help of electron localization fucntion ELF plots and spin resolved chemical bonding criteria.

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Section: Resultssupporting

confidence: 84%

Ab initiostudies of magnetic properties of cobalt and tetracobalt nitrideCo4N

2007

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“…However, a rough substrate will induce some interface roughness at the interface of two materials. This has already been observed for other systems for both single layer 10 and multilayer. 4 In our samples, interface roughness should be at least of the order of a nanometer.…”

supporting

confidence: 57%

Influence of surface/interface roughness and grain size on magnetic property of Fe∕Co bilayer

Aurongzeb

Ram

Menon

2005

Applied Physics Letters

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In this work, we report the influence of surface roughness and cluster size on coercivity of Fe∕Co bilayer. Coercivity was tuned by thermal annealing. No systematic trend was found for temperature dependent annealing. However, after annealing at 350 °C, we find systematic increase in coercivity with anneal time. For as-deposited film, we find unusually low coercivity (0.39 Oe). By increasing annealing time, coercivity was tuned to values as high as 600 Oe. Surface characterization using atomic force microscopy showed uniform clusters at this temperature after 2 h of annealing. The observed magnetic properties are discussed in terms of cluster size and surface/interface roughness.

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“…Values of H E and H C are 3.5 Oe and 12.4 Oe respectively, as obtained from M-H plots corresponding to both FC and ZFC (data not presented here). The small stray magnetic field which might have been present during the growth was enough to make this FM (Co) layer saturated at RT, bulk T C of Co being much greater than RT [41]. That is why every M-H loop starts with a positive M even when there is no applied filed (H = 0) in the SQUID measurements.…”

Section: Exchange Bias and Its Ion Beam Induced Evolutionmentioning

confidence: 97%

“…For the as-deposited film the magnetization is ~ 744 e.m.u./cm 3 . For bulk Co the value of magnetization is 1400 emu/cm 3 [41]. For thin films, this value is usually smaller.…”

Section: Exchange Bias and Its Ion Beam Induced Evolutionmentioning

confidence: 99%

“…/cm 3 have been reported [41]. As the M S value is found to depend on thickness [41], in order to study the ion beam induced effect unambiguously, we ensure that all the samples for irradiation are from the same source as the as-deposited film (cut from a 100 mm dia sample). (Table 2) is not constant but decreases with increase in ion fluence.…”

Section: Exchange Bias and Its Ion Beam Induced Evolutionmentioning

confidence: 99%

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Magnetic Exchange Bias and Its Ion Beam Induced Enhancement in a Nanoscale Si/Co/Si System

Roy¹,

Menyhárd²,

Majumdar³

et al. 2011

JMSE-A

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Abstract:Measurements of magnetic moment (M) as a function of applied magnetic field (H) have been carried out using a superconducting quantum interference device (SQUID) on an ultrathin bilayer film Si/Co, deposited on a silicon substrate. The M-H hysteresis loop has shown a shift with respect to the H = 0 axis due to the presence of a unidirectional or exchange anisotropy in the material. The amount of shift of the loop along the H axis, which is known as the exchange bias field H E has been measured for the as-grown as well as the ion irradiated samples. Ion irradiation was carried out with 2 MeV Cu ++ ions at different fluences ranging from 1×10 13 ions/cm 2 to 1×10 15 ions/cm 2 . The value of H E has been found to increase with increasing ion fluence. X-ray reflectivity (XRR) measurements on the as-grown as well as the ion irradiated samples show an increase in mixing of Si and Co at the Co/Si interfaces with the increase in fluence. Depth profile of different elements by Auger electron spectroscopy (AES) also supports this strong Si-Co mixing at the Si/Co interfaces. Ion beam induced enhancement of exchange bias has been attributed to a reduction of the thickness of the Co layer due to alloying at the interfaces as well as a reduction in the saturation magnetization due to incorporation of some Si into the Co layer. The interface exchange coupling energy has also been estimated for this system.

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Electron-beam evaporated cobalt films on molecular beam epitaxy prepared GaAs(001)

Cited by 14 publications

References 22 publications

Ab initiostudies of magnetic properties of cobalt and tetracobalt nitrideCo4N

Ab initiostudies of magnetic properties of cobalt and tetracobalt nitrideCo4N

Influence of surface/interface roughness and grain size on magnetic property of Fe∕Co bilayer

Magnetic Exchange Bias and Its Ion Beam Induced Enhancement in a Nanoscale Si/Co/Si System

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