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1

Digitale Medien

Domain wall trapping in controlled submicron ferromagnetic elements (2000)

Hirohata, A. ; Xu, Y. B. ; Yao, C. C. ; [weitere]

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 87 (2000), S. 4727-4729

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ISSN: 1089-7550

Quelle: AIP Digital Archive

Thema: Physik

Notizen: The domain configuration in permalloy wires (30 nm thick, 10 μm wide, and 205 μm long) with a wide size range of a narrow central bridge (5 μm long and w μm wide; 0.5≤w≤10 μm) were investigated in both their demagnetized and remanent states using magnetic force microscopy and the results were confirmed by micromagnetic calculations. At the bridge region, domain walls were found to be shifted by a small external field. Scanning magneto-optical Kerr effect revealed that the coercivity in these structures are the same as that in a straight wire, suggesting that domain wall movement is the dominant process in the magnetization reversal of these structures. © 2000 American Institute of Physics.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.373140

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2

Digitale Medien

Micromagnetism in mesoscopic epitaxial Fe dot arrays (2000)

Xu, Y. B. ; Hirohata, A. ; Lopez-Diaz, L. ; [weitere]

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 87 (2000), S. 7019-7021

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ISSN: 1089-7550

Quelle: AIP Digital Archive

Thema: Physik

Notizen: The domain structures of epitaxial Fe (20 nm)/GaAs(100) circular dot arrays (diameters from 50 to 1 μm) were studied with magnetic force microscopy. A transition from a single domain to a multidomain remanent state was observed upon reducing the dot diameter beneath 10 μm in dot arrays with the separation twice the dot diameter. When the separation is reduced to half the dot diameter, the single domain states were found to "collapse" into stripe-like multidomain states due to local dipole coupling between dots. Micromagnetic simulations further suggest that for ultrathin Fe dots of less than about 2 nm thickness the diameter does not have a significant influence on the domain structures due to a dramatic reduction of the dipole energy. © 2000 American Institute of Physics.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.372917

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3

Digitale Medien

Domain nucleation processes in mesoscopic Ni80Fe20 wire junctions (2000)

Lee, W. Y. ; Yao, C. C. ; Hirohata, A. ; [weitere]

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 87 (2000), S. 3032-3036

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ISSN: 1089-7550

Quelle: AIP Digital Archive

Thema: Physik

Notizen: The magnetization reversal process in permalloy (Ni80Fe20) wire junction structures has been investigated using magnetoresistance (MR) measurements and scanning Kerr microscopy. A combination of electron beam lithography and a lift-off process has been utilized to fabricate wires consisting of two 200 μm length regions with distinct widths w1 and w2 in the range 1–5 μm. Longitudinal MR measurements and magneto-optic Kerr effect hysteresis loops demonstrate that the magnetization reversal of the complete structure is predominantly determined by the wider region for fields applied parallel to the wire axis. Magnetic force microscopy and micromagnetic calculations show that several domain walls nucleate in the wider part and are trapped in the junction area. This implies that domain nucleation at the junction of the wire initiates magnetization reversal in the narrow half. As a consequence, the switching fields are found to be identical in both halves in this case. These results suggest the possibility of designing structures which can be used to "launch" reverse domains in narrow wires within a controlled field range. © 2000 American Institute of Physics.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.372295

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4

Digitale Medien

Sweep rate-dependent magnetization reversal in epitaxial Fe/GaAs(001) and Fe/InAs(001) thin films (2000)

Lee, W. Y. ; Xu, Y. B. ; Gardiner, S. M. ; [weitere]

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 87 (2000), S. 5926-5928

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ISSN: 1089-7550

Quelle: AIP Digital Archive

Thema: Physik

Notizen: We present the magnetization reversal dynamics of epitaxial Fe thin films grown on GaAs(001) and InAs(001) studied as a function of field sweep rate in the range 0.01–160 kOe/s using magneto-optic Kerr effect. For 55 and 250 Å Fe/GaAs(001), we find that the hysteresis loop area A follows the scaling relation A∝H(overdot)α with α=0.03–0.05 at low sweep rates and 0.33–0.40 at high sweep rates. For the 150 Å Fe/InAs(001) film, α is found to be ∼0.02 at low sweep rates and ∼0.17 at high sweep rates. The differing values of α are attributed to a change of the magnetization reversal process with increasing sweep rate. © 2000 American Institute of Physics.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.372569

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5

Digitale Medien

Cardiovascular Instability Induced by Intracerebroventricular Administration of Vasopressin or Corticotrophin-Releasing Factor in Conscious Long Evans and Brattleboro Rats (1990)

Gardiner, S. M. ; Compton, A. M. ; Bennett, T.

Oxford, UK : Blackwell Publishing Ltd

Journal of neuroendocrinology 2 (1990), S. 0

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ISSN: 1365-2826

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Medizin

Notizen: Conscious Long Evans and Brattleboro rats, chronically instrumented with pulsed Doppler probes around left renal and superior mesenteric arteries and the distal abdominal aorta, had vasopressin or corticotrophin-releasing factor administered intracerebroventricularly. In Long Evans rats, vasopressin caused no cardiovascular instability, but in Brattleboro rats, vasopressin caused the development of marked oscillations in blood pressure and heart rate. Under the latter conditions, falls in blood pressure were accompanied by increases in hindquarter blood flow. Similar oscillations in blood pressure, heart rate and regional haemodynamics were seen in Long Evans and Brattleboro rats given corticotrophin-releasing factor. These results indicate that centrally-administered vasopressin and corticotrophin-releasing factor can have an important influence on the control of regional haemodynamics. In some respects the effects of the peptides resemble the changes seen during the defence reaction.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/j.1365-2826.1990.tb00390.x

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6

Digitale Medien

Cardiovascular and Steroid Responses to Graded Haemorrhage in Rats with Adrenal Regeneration Hypertension (1990)

Foulkes, R. ; Gardiner, S. M. ; Bennett, T.

Oxford, UK : Blackwell Publishing Ltd

Journal of neuroendocrinology 2 (1990), S. 0

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ISSN: 1365-2826

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Medizin

Notizen: Blood pressure (BP) and plasma steroid responses to haemorrhage (2 ml + 1 ml + 1 ml at 20-min intervals) were assessed in sham-operated (SO) rats and in rats with adrenal regeneration hypertension (ARH). Experiments were carried out between 0700 and 1000 h (a.m.) and between 1400 and 1700 h (p.m.), because rats with ARH have BPs that are higher a.m. than p.m. There were no differences in the BP responses following haemorrhage in SO or ARH rats either a.m. or p.m., although ARH rats were unable to increase their plasma steroid levels. Pretreatment with captopril alone, d(CH2)5 DAVP alone, or captopril and d(CH2)5DAVP augmented the early hypotensive responses to haemorrhage but did not influence the later compensated levels of BP in either group of rats. There were no clear-cut a.m. to p.m. differences in the changes in BP in any of the drug-treated groups of SO or ARH rats. Under all conditions studied, the compensated level of systolic BP in ARH rats, 20 min after the final bleed, remained higher a.m. than p.m., indicating that this difference was not dependent on the renin-angiotensin system and vasopressin and suggesting that the sympathetic nervous system and/or other factors might be involved.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/j.1365-2826.1990.tb00391.x

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7

Digitale Medien

Excessive placental secretion of neurokinin B during the third trimester causes pre-eclampsia (2000)

Page, N. M. ; Woods, R. J. ; Gardiner, S. M. ; [weitere]

[s.l.] : Macmillian Magazines Ltd.

Nature 405 (2000), S. 797-800

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ISSN: 1476-4687

Quelle: Nature Archives 1869 - 2009

Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik

Notizen: [Auszug] Pre-eclampsia is a principal cause of maternal morbidity and mortality, affecting 5–10% of first pregnancies worldwide. Manifestations include increased blood pressure, proteinuria, coagulopathy and peripheral and cerebral oedema. Although the aetiology and pathogenesis remain to be ...

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1038/35015579

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