Non-inversion anisotropy energy in NiO coral structure: Asymmetric hysteresis loop at room temperature

Bhattacharjee, Swarupananda; Das, G. C.; Roychowdhury, Anirban; Das, Dipankar; Ghosh, Chandan Kumar; Bhattacharya, Dipten; Sen, Pintu

doi:10.1016/j.apsusc.2018.01.023

Cited by 4 publications

(2 citation statements)

References 74 publications

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“…In addition to the most typical EB system, composed of a ferromagnet exchange-coupled to an antiferromagnet, there are also less usual material combinations or even pure materials that are able to exhibit an exchange bias, such as the recently found NiMn 2 O 4 [23,24]. Similarly, in several material systems, it cannot be excluded that ferromagnetic clusters form in antiferromagnetic metal oxides, or that the surface of a ferromagnetic metal is unintentionally oxidized to an antiferromagnetic state [25,26]. These effects, however, cannot explain the asymmetry found here-the system Co/CoO is well-known as an exchange bias system, however, not at temperatures above the blocking temperature.…”

Section: Discussionmentioning

confidence: 99%

Asymmetric Hysteresis Loops in Co Thin Films

Ehrmann

Błachowicz

2020

Condensed Matter

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Asymmetric magnetic hysteresis loops are usually found in exchange bias (EB) systems, typically after field cooling a system below the Néel temperature of an antiferromagnet exchange coupled to a ferromagnet. Alternatively, asymmetric hysteresis loops may occur due to undetected minor loops or in systems with a rotational anisotropy. Here, we report on an exchange bias thin film system MgO(100)/Co/CoO, examined at room temperature, which is far above the blocking temperature, by the magneto-optical Kerr effect (MOKE). While the longitudinal hysteresis loops partly show steps which are well-known from diverse purely ferromagnetic systems, the transverse hysteresis loops exhibit clear asymmetries, similar to exchange biased systems at low temperatures, and unusual transverse magnetization values at saturation. Since minor loops and a rotational anisotropy can be excluded in this case, this asymmetry can possibly be a residue of the exchange bias coupling at lower temperatures.

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Section: Discussionmentioning

confidence: 99%

Asymmetric Hysteresis Loops in Co Thin Films

Ehrmann

Błachowicz

2020

Condensed Matter

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“…To understand the nature and concentration of the intrinsic defects (both anionic and cationic), the nanoflowers were investigated by positron annihilation lifetime spectroscopy (PALS), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectroscopy. , As presented in Table , defect analyses using the two-state positron trapping model (detailed in the Supplementary Information) reveal the existence of three lifetimes (τ 1 , τ 2 , and τ 3 ) of positron annihilation along with their relative intensities ( I 1 , I 2 , and I 3 ). The longest lifetime (τ 3 ) could be assigned to the annihilation of orthopositronium atoms, i.e., the hydrogen-like quasiparticle of an electron and positron pair with the same spin, formed at larger voids within the materials.…”

Section: Resultsmentioning

confidence: 99%

Trapped Exciton-Enhanced Response of n-TiO₂(110)/p-Si(111) Nanostructures as Photodetectors

Bhattacharya

Dey

Islam

et al. 2022

ACS Appl. Nano Mater.

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A p-type Si(111)/n-TiO2(110) heterojunction photodetector device has been fabricated for broad spectral range detection. An environmentally friendly NaCl assisted hydrothermal route was employed for synthesizing an n-type TiO2(110) hierarchical nanostructure powder. A 1 μm thick film of TiO2 was then deposited by spin coating on the top of p-type Si(111). The role of NaCl in tuning both anionic (oxygen vacancy) and cationic (Ti mono- and divacancy, Ti interstitials) defects has been investigated. The vacancies posed a significant effect on photoresponse and junction characteristics of the device, viz., dark current, barrier height, photosensitivity, detectivity, and photoresponse gain. The TiO2 n-type layer fabricated at higher NaCl concentrations has been found to exhibit maximum responsivity of ∼550 A/W, gain of ∼2.00, specific detectivity of ∼1.27 × 1011 Jones, and fast response and recovery times of 38 and 43 ms, respectively. The device has been highly repeatable (for 12 cycles) with a stability of 60 days. These have been ascribed to the exciton, formed at the bridged oxygen adjacent to the Ti vacancy at the (110) surface. We have also resolved that the charge carrier–phonon interaction facilitates exciton stabilization, while the charge transfer across the interface follows the adiabatic process. To explain the variation of device performance with defects, a mathematical model has been proposed to correlate the device responsivity to the different vacancies.

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Unravelling the role of cationic Ni2+ vacancies and Ni3+ ions in non-stoichiometric NiO: breakdown of anti-ferromagnetic ordering and large exchange bias

Bhanuchandar,

Vinothkumar,

Arunkumar

et al. 2023

J Mater Sci

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Non-inversion anisotropy energy in NiO coral structure: Asymmetric hysteresis loop at room temperature

Cited by 4 publications

References 74 publications

Asymmetric Hysteresis Loops in Co Thin Films

Asymmetric Hysteresis Loops in Co Thin Films

Trapped Exciton-Enhanced Response of n-TiO₂(110)/p-Si(111) Nanostructures as Photodetectors

Unravelling the role of cationic Ni2+ vacancies and Ni3+ ions in non-stoichiometric NiO: breakdown of anti-ferromagnetic ordering and large exchange bias

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Non-inversion anisotropy energy in NiO coral structure: Asymmetric hysteresis loop at room temperature

Cited by 4 publications

References 74 publications

Asymmetric Hysteresis Loops in Co Thin Films

Asymmetric Hysteresis Loops in Co Thin Films

Trapped Exciton-Enhanced Response of n-TiO2(110)/p-Si(111) Nanostructures as Photodetectors

Unravelling the role of cationic Ni2+ vacancies and Ni3+ ions in non-stoichiometric NiO: breakdown of anti-ferromagnetic ordering and large exchange bias

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Trapped Exciton-Enhanced Response of n-TiO₂(110)/p-Si(111) Nanostructures as Photodetectors