Resonant magneto-optical properties of Fe near its<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mn>2</mml:mn><mml:mi>p</mml:mi></mml:math>levels: Measurement and applications

Kortright, Jeffrey B.; Kim, Sang‐Koog

doi:10.1103/physrevb.62.12216

Cited by 182 publications

(236 citation statements)

References 54 publications

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“…The boundary of the magnetic domain patterns are enhanced at a photon energy of 705eV and 711eV, where no 11 absorption contrast is expected. The observed reversal of contrast is in agreement with measurements of the magnetic real part of the refractive index [35].…”

Section: Resultssupporting

confidence: 79%

Exploring nanomagnetism with soft X-ray microscopy

et al. 2007

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Magnetic soft X-ray microscopy images magnetism in nanoscale systems with a spatial resolution down to 15nm provided by state-of-the-art Fresnel zone plate optics. X-ray magnetic circular dichroism (X-MCD) is used as element-specific magnetic contrast mechanism similar to photoemission electon microscopy (PEEM), however, with volume sensitivity and the ability to record the images in varying applied magnetic fields which allows to study magnetization reversal processes at fundamental length scales. Utilizing a stroboscopic pump-probe scheme one can investigate fast spin dynamics with a time resolution down to 70 ps which gives access to precessional and relaxation phenomena as well as spin torque driven domain wall dynamics in nanoscale systems. Current developments in zone plate optics aim for a spatial resolution towards 10nm and at next generation X-ray sources a time resolution in the fsec regime can be envisioned.Keywords magnetic soft X-ray microscopy, X-ray optics, Fresnel zone plates, magnetic nanostructures, magnetization reversal, fast spin dynamics, X-ray magnetic circular dichroism 3

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Section: Resultssupporting

confidence: 79%

Exploring nanomagnetism with soft X-ray microscopy

et al. 2007

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“…∆ is the optical index of up ( + ) and down ( − ) magnetic domains 35 , d is the thickness of the film and, λ is the wavelength of the radiation. Developing expression 3, we find that I is proportional to …”

Section: Where G(t) Is the Gaussian Function H(t)mentioning

confidence: 99%

Laser-induced ultrafast demagnetization in the presence of a nanoscale magnetic domain network

et al. 2012

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Femtosecond magnetization phenomena have been challenging our understanding for over a decade. most experiments have relied on infrared femtosecond lasers, limiting the spatial resolution to a few micrometres. With the advent of femtosecond X-ray sources, nanometric resolution can now be reached, which matches key length scales in femtomagnetism such as the travelling length of excited 'hot' electrons on a femtosecond timescale. Here we study laser-induced ultrafast demagnetization in [Co/Pd] 30 multilayer films, which, for the first time, achieves a spatial resolution better than 100 nm by using femtosecond soft X-ray pulses. This allows us to follow the femtosecond demagnetization process in a magnetic system consisting of alternating nanometric domains of opposite magnetization. no modification of the magnetic structure is observed, but, in comparison with uniformly magnetized systems of similar composition, we find a significantly faster demagnetization time. We argue that this may be caused by direct transfer of spin angular momentum between neighbouring domains.

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“…Lee et al (2001) found that the edge structure in MCG-6-30-15 matches very well that found in Cyg X-1. Schulz et al (2002) showed that the Cyg X-1 edge could be fairly accurately reproduced if the Fe resides in pure Fe grains (taking experimental data from Kortright & Kim 2000), but not if the Fe is in oxides (taking data from Crocombette et al 1995). A measurement of the oxygen column in the dust could not be made for Cyg X-1, as the large O  edge (τ > 2) was dominated by neutral oxygen in the ISM along the line-of-sight.…”

Section: Compositionmentioning

confidence: 99%

On the location and composition of the dust in the MCG–6-30-15 warm absorber

Ballantyne¹,

Weingartner²,

Murray³

2003

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Abstract. The warm absorber observed in the Seyfert 1 galaxy MCG-6-30-15 is known to consist of at least two zones and very likely contains dust. Hubble Space Telescope images of MCG-6-30-15 show a dust lane crossing the galaxy just below the nucleus. In this paper, we argue that this dust lane is responsible for the observed reddening of the nuclear emission and the Fe  edge hinted at in the Chandra spectrum of MCG-6-30-15. We further suggest that the gas within the dust lane can comprise much of the low ionization component (i.e., the one contributing the O  edge) of the observed warm absorber. Moreover, placing the warm absorbing material at such distances (hundreds of pc) can account for the small outflow velocities of the low ionization absorption lines as well as the constancy of the O  edge. Photoionization models of a dusty interstellar gas cloud (with a column appropriate for the reddening toward MCG-6-30-15) using a toy Seyfert 1 spectral energy distribution show that it is possible to obtain a significant O  edge (τ ∼ 0.2) if the material is ∼150 pc from the ionizing source. For MCG-6-30-15, such a distance is consistent with the observed dust lane. We emphasize the point first made by Kraemer et al.: dusty interstellar material will likely contribute to the warm absorber, and should be included in spectral modeling. The current data on MCG-6-30-15 is unable to constrain the dust composition within the warm absorber. Astronomical silicate is a viable candidate, but there are indications of a very low O abundance in the dust, which is inconsistent with a silicate origin. If true, this may indicate that there were repeated cycles of grain destruction and growth from shocks in the interstellar medium of MCG-6-30-15. Pure iron grains are an unlikely dust constituent due to the limit on their abundance in the Galaxy, yet they cannot be ruled out. The high column densities inferred from the highly ionized zone of the warm absorber implies that this gas is dust-free.

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Resonant magneto-optical properties of Fe near its2plevels: Measurement and applications

Cited by 182 publications

References 54 publications

Exploring nanomagnetism with soft X-ray microscopy

Exploring nanomagnetism with soft X-ray microscopy

Laser-induced ultrafast demagnetization in the presence of a nanoscale magnetic domain network

On the location and composition of the dust in the MCG–6-30-15 warm absorber

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