Magnetism in hafnium dioxide

Coey, J. M. D.; Venkatesan, M.; Stamenov, Plamen; Fitzgerald, C. B.; Dorneles, L. S.

doi:10.1103/physrevb.72.024450

Cited by 428 publications

(319 citation statements)

References 21 publications

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“…Difficult issues include the high Curie temperature, [6][7][8][9] the origin of large and anisotropic saturation magnetization in some systems, 7,9 and the specific role of imperfections such as oxygen vacancies, substitutional disorder, and interstitial occupancies. [4][5][6][7]11 These questions have far-reaching ramifications. For example, the anisotropic magnetic moment observed in Co-doped ZnO ͑Ref.…”

Section: Introductionmentioning

confidence: 99%

Temperature-dependent orbital-moment anisotropy in dilute magnetic oxides

Zhang

Skomski

et al. 2007

Phys. Rev. B

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A striking magnetization anisotropy in thin films of vanadium-doped stannic oxide is reported and investigated. The single-crystalline Sn 1−x V x O 2 ͑0 ഛ x ഛ 0.1͒ thin films, grown on Al 2 O 3 substrate, are ͑101͒ oriented and exhibit a temperature-dependent in-plane anisotropy of the saturation magnetization. The in-plane magnetic moment reaches a maximum close to the ͓101͔ direction, but the anisotropy axis is incompatible with the crystalline structure of the SnO 2 thin films. However, it is consistent with V atoms occupying uniaxially distorted octahedral interstices, thus breaking the symmetry of the film. The moment anisotropy decreases gradually with increasing temperature and persists to temperatures above room temperature. It is modeled as a spin-orbit effect involving the hopping of orbital-current loops, as contrasted to isotropic Heisenberg exchange, and the temperature dependence of the magnetism is explained on the basis of a thermal admixture of nearly degenerate crystal-field states. The phenomena may be relevant to a wide range of dilute magnetic oxides.

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Section: Introductionmentioning

confidence: 99%

Temperature-dependent orbital-moment anisotropy in dilute magnetic oxides

Zhang

Skomski

et al. 2007

Phys. Rev. B

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“…4 Nevertheless, the cationic vacancies induced RTFM order in HfO 2 was later questioned as the diamagnetic HfO 2 powder exhibited weak ferromagnetic order after annealing in vacuum at 750 C for 2 h, which in turn suggested origin of FM to be related to oxygen vacancies. 5 Hong et al 6 observed RTFM in TiO 2 , HfO 2 , and In 2 O 3 , and reported that the annealing of HfO 2 and TiO 2 films in oxygen ambient degraded/destroyed ferromagnetic ordering. They suggested that both oxygen vacancies and confinement effects were key factors in inducing RTFM order.…”

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confidence: 99%

“…Our findings are consistent with the oxygen vacancies induced RTFM spin-order reported in oxides such as HfO 2 , TiO 2 , and ZnO, etc. 5,6 Fig . 2 shows PL emission spectra of MgO nanocrystallites for the samples calcined for 2 h each at 600 C (in air or oxygen) and 1000 C (in air) recorded with excitation wavelengths of 350 nm.…”

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confidence: 99%

Defect and adsorbate induced ferromagnetic spin-order in magnesium oxide nanocrystallites

Кумар

Kumar

Priya

2012

Applied Physics Letters

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We report the correlation between d0 ferromagnetism, photoluminescence (PL), and adsorbed hydrogen (H−) species in magnesium oxide (MgO) nanocrystallites. Our study suggests that the oxygen vacancies, namely singly ionized anionic vacancies (F+) and dimers (F22+) induce characteristic photoluminescence and the room-temperature ferromagnetic spin-order. Nanocrystallites with low population of oxygen vacancies have revealed diamagnetic behavior. Intriguingly, on adsorption of hydrogen (H−) species in the MgO nanocrystallites, ferromagnetic behavior was either enhanced (in the case of highly oxygen deficient nanocrystallites) or begun to percolate (in the case of nanocrystallite with low population density of oxygen vacancies).

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“…12,13 At higher concentrations, they overlap to form an impurity band which is quite distinct from that formed by any dopants that may be present. The nature of the magnetic coupling of such defects needs to be investigated, especially in view the huge anisotropy of the saturation magnetization in some cases, 5,6,[9][10][11] which points to magnetic moments of largely orbital character. It is worth noting that a huge, strongly-anisotropic susceptibility has been observed for polyalanine molecules absorbed on a gold-plated silicon wafer.…”

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confidence: 99%

High-temperature ferromagnetism in dilute magnetic oxides

Coey¹

2005

Journal of Applied Physics

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111

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High temperature ferromagnetism in thin films of dilute magnetic oxides is a widespread phenomenon, of which there appear to be two sources. One is the contribution of the 3d dopant ions themselves, the other is related to crystal defects in the interface region. The latter contributes a magnetic moment of 100–400μB per square nanometer of substrate area, which is largely independent of film thickness or dopant concentration. It is suggested that the defects are two-electron or two-hole centers which have a spin triplet as ground state or low-lying excited state. HfO2, an example of the former, is ferromagnetic even when undoped. In ZnO or SnO2, examples of the latter, the magnetic dopant may stabilize the spin triplet by exchange.

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Magnetism in hafnium dioxide

Cited by 428 publications

References 21 publications

Temperature-dependent orbital-moment anisotropy in dilute magnetic oxides

Temperature-dependent orbital-moment anisotropy in dilute magnetic oxides

Defect and adsorbate induced ferromagnetic spin-order in magnesium oxide nanocrystallites

High-temperature ferromagnetism in dilute magnetic oxides

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