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Petr Opletal: Preparation and characterization of UCoGa in the context of quantum phase transitions
Begin: 03.05.2017, 14:30
Location: lecture room F2, first floor Ke Karlovu 5

Mgr. Lukáš Horák

Místnost
F 048, přízemí, Ke Karlovu 5
Telefon
+420  22191 1455
Fax
+420  22491 1061
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Bibliografie:

L Horak, J Matejova, X Marti, V Holy, V Novak, Z Soban, S Mangold and F Jimenez-Villacorta. Diffusion of Mn interstitials in (Ga,Mn)As epitaxial layers. PHYSICAL REVIEW B 83(24), 2011. BibTeX

@article{ ISI:000292183300005,
	author = "Horak, L. and Matejova, J. and Marti, X. and Holy, V. and Novak, V. and Soban, Z. and Mangold, S. and Jimenez-Villacorta, F.",
	title = "{Diffusion of Mn interstitials in (Ga,Mn)As epitaxial layers}",
	journal = "{PHYSICAL REVIEW B}",
	year = "{2011}",
	volume = "{83}",
	number = "{24}",
	month = "{JUN 28}",
	abstract = "{The magnetic properties of thin (Ga,Mn) As layers improve during annealing by out-diffusion of interstitialMn ions to a free surface. Out-diffused Mn atoms participate in the growth of aMn-rich surface layer and a saturation of this layer causes an inhibition of the out-diffusion. We combine high-resolution x-ray diffraction with x-ray absorption spectroscopy and a numerical solution of the diffusion problem for the study of the out-diffusion of Mn interstitials during a sequence of annealing steps. Our data demonstrate that the out-diffusion of the interstitials is substantially affected by the internal electric field caused by an inhomogeneous distribution of charges in the (Ga,Mn) As layer.}",
	doi = "{10.1103/PhysRevB.83.245209}",
	article-number = "{245209}",
	issn = "{1098-0121}",
	researcherid-numbers = "{Jimenez-Villacorta, Felix/C-3924-2009}",
	times-cited = "{1}",
	unique-id = "{ISI:000292183300005}"
}

C S King, J Zemen, K Olejnik, L Horak, J A Haigh, V Novak, A Irvine, J Kucera, V Holy, R P Campion, B L Gallagher and T Jungwirth. Strain control of magnetic anisotropy in (Ga,Mn)As microbars. PHYSICAL REVIEW B 83(11), 2011. BibTeX

@article{ ISI:000288242800006,
	author = "King, C. S. and Zemen, J. and Olejnik, K. and Horak, L. and Haigh, J. A. and Novak, V. and Irvine, A. and Kucera, J. and Holy, V. and Campion, R. P. and Gallagher, B. L. and Jungwirth, T.",
	title = "{Strain control of magnetic anisotropy in (Ga,Mn)As microbars}",
	journal = "{PHYSICAL REVIEW B}",
	year = "{2011}",
	volume = "{83}",
	number = "{11}",
	month = "{MAR 11}",
	abstract = "{We present an experimental and theoretical study of magnetocrystalline anisotropies in arrays of bars patterned lithographically into (Ga,Mn) As epilayers grown under compressive lattice strain. Structural properties of the (Ga,Mn) As microbars are investigated by high-resolution x-ray diffraction measurements. The experimental data, showing strong strain relaxation effects, are in good agreement with finite element simulations. Magnetization measurements are performed using a superconducting quantum interference device to study the control of magnetic anisotropy in (Ga,Mn) As by the lithographically induced strain relaxation of the microbars. Microscopic theoretical modeling of the anisotropy is performed based on the mean-field kinetic-exchange model of the ferromagnetic spin-orbit coupled band structure of (Ga,Mn) As. Based on the overall agreement between experimental data and theoretical modeling, we conclude that the micropatterning induced anisotropies are of magnetocrystalline, spin-orbit coupling origin.}",
	doi = "{10.1103/PhysRevB.83.115312}",
	article-number = "{115312}",
	issn = "{1098-0121}",
	researcherid-numbers = "{Olejnik, Kamil/I-7085-2012}",
	times-cited = "{2}",
	unique-id = "{ISI:000288242800006}"
}

V Holy, X Marti, L Horak, O Caha, V Novak, M Cukr and T U Schuelli. Density of Mn interstitials in (Ga,Mn)As epitaxial layers determined by anomalous x-ray diffraction. APPLIED PHYSICS LETTERS 97(18), 2010. BibTeX

@article{ ISI:000283934100025,
	author = "Holy, V. and Marti, X. and Horak, L. and Caha, O. and Novak, V. and Cukr, M. and Schuelli, T. U.",
	title = "{Density of Mn interstitials in (Ga,Mn)As epitaxial layers determined by anomalous x-ray diffraction}",
	journal = "{APPLIED PHYSICS LETTERS}",
	year = "{2010}",
	volume = "{97}",
	number = "{18}",
	month = "{NOV 1}",
	abstract = "{Densities of Mn ions in epitaxial layers of (Ga,Mn)As were determined by anomalous x-ray diffraction, i.e., by a measurement of the dependence of the intensity of weak diffraction 002 on the photon energy around the Mn K absorption edge. From the measured data it was possible to determine the density of Mn ions in substitutional positions and the difference in the Mn densities in two possible interstitial positions in the GaAs lattice. The data demonstrate that the rate of the out-diffusion of the Mn interstitials from the Ga tetrahedrons significantly exceeds that from the As tetrahedrons. (C) 2010 American Institute of Physics. {[}doi:10.1063/1.3514240]}",
	doi = "{10.1063/1.3514240}",
	article-number = "{181913}",
	issn = "{0003-6951}",
	researcherid-numbers = "{Caha, Ondrej/E-4716-2012}",
	times-cited = "{1}",
	unique-id = "{ISI:000283934100025}"
}

L Horak, Z Soban and V Holy. Study of Mn interstitials in (Ga, Mn) As using high-resolution x-ray diffraction. JOURNAL OF PHYSICS-CONDENSED MATTER 22(29), 2010. BibTeX

@article{ ISI:000279616000034,
	author = "Horak, L. and Soban, Z. and Holy, V.",
	title = "{Study of Mn interstitials in (Ga, Mn) As using high-resolution x-ray diffraction}",
	journal = "{JOURNAL OF PHYSICS-CONDENSED MATTER}",
	year = "{2010}",
	volume = "{22}",
	number = "{29}",
	month = "{JUL 28}",
	abstract = "{We present a method for the determination of the concentration of Mn ions in nonequivalent interstitial positions in the lattice of (Ga, Mn) As. The Mn ions occupy substitutional and/or interstitial positions in the GaAs lattice and the dependence of the structure factor on their concentration differs for various diffractions and for different positions in the lattice. We measured several diffractions including weak diffractions, which are very sensitive to the Mn content. All measured diffraction curves were simultaneously fitted to a theoretical model and the densities of Mn ions, in particular interstitial positions, were obtained. The method reported here allows us to determine the amount of interstitial Mn which, according to current understanding, affects the ferromagnetic properties including the Curie temperature in (Ga, Mn) As.}",
	doi = "{10.1088/0953-8984/22/29/296009}",
	article-number = "{296009}",
	issn = "{0953-8984}",
	times-cited = "{2}",
	unique-id = "{ISI:000279616000034}"
}

L Horak, V Holy, C R Staddon, N R S Farley, S V Novikov, R P Campion and C T Foxon. X-ray in-plane scattering investigation of GaN nanorods. JOURNAL OF APPLIED PHYSICS 104(10), 2008. BibTeX

@article{ ISI:000262605800031,
	author = "Horak, L. and Holy, V. and Staddon, C. R. and Farley, N. R. S. and Novikov, S. V. and Campion, R. P. and Foxon, C. T.",
	title = "{X-ray in-plane scattering investigation of GaN nanorods}",
	journal = "{JOURNAL OF APPLIED PHYSICS}",
	year = "{2008}",
	volume = "{104}",
	number = "{10}",
	month = "{NOV 15}",
	abstract = "{An x-ray method is described for the structure characterization of semiordered GaN nanorods. In contrast to other works based on synchrotron radiation, the method uses a standard x-ray laboratory equipment so that it is suitable for a rapid characterization of the nanorods in a technological laboratory. The method uses a grazing-incidence diffraction setup and it makes it possible to determine the mean size of the rods and their angular twist with respect to the crystalline substrate. The applicability of the method is demonstrated on a series of GaN nanorod samples and the parameters of the nanorods are compared with the results of scanning electron microscopy.}",
	doi = "{10.1063/1.3021090}",
	article-number = "{103504}",
	issn = "{0021-8979}",
	times-cited = "{3}",
	unique-id = "{ISI:000262605800031}"
}

J Krcmar, V Holy, L Horak, T H Metzger and J Sobota. Standing-wave effects in grazing-incidence x-ray diffraction from polycrystalline multilayers. JOURNAL OF APPLIED PHYSICS 103(3), 2008. BibTeX

@article{ ISI:000253238100017,
	author = "Krcmar, J. and Holy, V. and Horak, L. and Metzger, T. H. and Sobota, J.",
	title = "{Standing-wave effects in grazing-incidence x-ray diffraction from polycrystalline multilayers}",
	journal = "{JOURNAL OF APPLIED PHYSICS}",
	year = "{2008}",
	volume = "{103}",
	number = "{3}",
	month = "{FEB 1}",
	abstract = "{The intensity of x-ray diffraction from a polycrystalline multilayer in a grazing-incidence scattering geometry is modulated by a standing wave created by the interference of the radiation transmitted through the multilayer stack with the wave field specularly reflected from the superlattice interfaces. Similarly, the radiation being diffracted from the polycrystalline structure is reflected specularly from the interfaces and a standing-wave interference pattern results as well. This effect is demonstrated by a series of diffraction measurements on C/Ni periodic multilayers; the experimental data have been modeled using the distorted-wave Born approximation and a very good correspondence with the experiments was achieved. The method was used for the study of the profiles of the crystallite sizes and strains in multilayers. (c) 2008 American Institute of Physics.}",
	doi = "{10.1063/1.2836974}",
	article-number = "{033504}",
	issn = "{0021-8979}",
	researcherid-numbers = "{Sobota, Jaroslav/D-5192-2012}",
	times-cited = "{1}",
	unique-id = "{ISI:000253238100017}"
}

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