Giant magnetoresistance (GMR) in electrodeposited multilayer films: the influence of superparamagnetic regions

When preparing an alternating sequence of magnetic (Co or Ni) and non-magnetic (Cu) layers by electrodeposition using the two-pulse plating technique, a dissolution of the lessnoble magnetic Co and Ni atoms can take place during the deposition of the more noble and non-magnetic Cu atoms. This process results in changes of the actual sublayer thicknesses with respect to the nominal values and can also cause some chemical intermixing at the magnetic/non-magnetic interfaces. As a consequence, superparamagnetic (SPM) regions with “loose magnetic moments” can form as has been demonstrated for electrodeposited Ni-Cu/Cu multilayers. We have also shown recently for electrodeposited Co-Cu/Cu multilayers that if some fraction of the magnetic layers exhibits SPM behaviour then the observed giant magnetoresistance (GMR) can be quantitatively decomposed into a ferromagnetic (FM) and a SPM contribution. In this paper, the results of a similar GMR decomposition study are presented for two electrodeposited Co-Cu/Cu multilayers. In the multilayer with strongly non-saturated magnetoresistance curves, the dominant GMR term was due to SPM regions, whereas in the other multilayer for which the magnetoresistance is mostly saturated in magnetic fields around 1 to 2 kOe, the FM contribution to the GMR is much larger. At the same time, magnetic measurements on the first multilayer sample have also revealed the presence of a large SPM contribution to the magnetization

A Linear Iterative Unfolding Method

A frequently faced task in experimental physics is to measure the probability distribution of some quantity. Often this quantity to be measured is smeared by a non-ideal detector response or by some physical process. The procedure of removing this smearing effect from the measured distribution is called unfolding, and is a delicate problem in signal processing, due to the well-known numerical ill behavior of this task. Various methods were invented which, given some assumptions on the initial probability distribution, try to regularize the unfolding problem. Most of these methods definitely introduce bias into the estimate of the initial probability distribution. We propose a linear iterative method, which has the advantage that no assumptions on the initial probability distribution is needed, and the only regularization parameter is the stopping order of the iteration, which can be used to choose the best compromise between the introduced bias and the propagated statistical and systematic errors. The method is consistent: "binwise" convergence to the initial probability distribution is proved in absence of measurement errors under a quite general condition on the response function. This condition holds for practical applications such as convolutions, calorimeter response functions, momentum reconstruction response functions based on tracking in magnetic field etc. In presence of measurement errors, explicit formulae for the propagation of the three important error terms is provided: bias error, statistical error, and systematic error. A trade-off between these three error terms can be used to define an optimal iteration stopping criterion, and the errors can be estimated there. We provide a numerical C library for the implementation of the method, which incorporates automatic statistical error propagation as well.Comment: Proceedings of ACAT-2011 conference (Uxbridge, United Kingdom), 9 pages, 5 figures, changes of corrigendum include

Recovering a spinning inspiralling compact binary waveform immersed in LIGO-like noise with spinning templates

We investigate the recovery chances of highly spinning waveforms immersed in LIGO S5-like noise by performing a matched filtering with 10^6 randomly chosen spinning waveforms generated with the LAL package. While the masses of the compact binary are reasonably well recovered (slightly overestimated), the same does not hold true for the spins. We show the best fit matches both in the time-domain and the frequency-domain. These encompass some of the spinning characteristics of the signal, but far less than what would be required to identify the astrophysical parameters of the system. An improvement of the matching method is necessary, though may be difficult due to the noisy signal.Comment: 5 pages, 1 figure + 4 figure panels; Proceedings of the Eight Edoardo Amaldi Conference on Gravitational Waves (Amaldi8), New York, 2009; to be published in J. Phys.: Conf. Series (JPCS

[Rezension zu:] Mária Bieliková: Bipolarität der Gestalten in Hermann Hesses Prosa

Rezension zu Mária Bieliková: Bipolarität der Gestalten in Hermann Hesses Prosa. Die Romane Demian und Der Steppenwolf vor dem Hintergrund der daoistischen Philosophie. Hamburg: Dr. Kovač, 200

Alapkutatások a tudománytörténet és a művelődéstörténet határterületein = Interdisciplinary basic research in the history of science and culture

Kutatásom első két évében a művelődéstörténész és gyógyszerészet-történész Ernyey József teljes hagyatékát dolgoztam fel, amely az Országos Széchényi Könyvtárban, a Természettudományi Múzeumban és a Néprajzi Múzeumban található. Gondos kutatómunkával sikerült összeállítani a teljes Ernyey-bibliográfiát is. Kéziratos anyagai és az azok tömörítéséből készült publikációi egybevetésével sikerült áttekintést adni történelmi, nyelvészeti és gyógyszerészeti kutatásairól. Ő volt a Természettudományi Múzeum első főigazgatója, nevét viseli Budapesten a Gyógyszerészettörténeti Könyvtár. Életművét most első alkalommal sikerült önálló monográfia formájában feldolgozni. Kutatásom második két évében Ács Tivadar művelődéstörténész hagyatékát dolgoztam fel, amely részben a Magyar Országos Levéltárban, részben Szegeden a Somogyi Könyvtárban található. Ács kéziratos anyagait összevetettem az elsősorban az amerikai magyar lapokban közölt cikkeivel, s kiegészítettem azokat az újabb kutatási eredményekkel, valamint a kéziratban maradt bibliográfiai jegyzeteit hozzácsatoltam kutatási anyagaihoz. Ács Tivadar életművéről ez az első átfogó kutatás. | In the first two years of my research I analysed the legacy of Jozsef Ernyei who was a historian of civilization and pharmaceutics. His legacy can be found in the National Széchényi Library, in the Museum of Natural Sciences and in the Museum of Ethnography. I managed to put together the full Ernyei bibliography as well as to give an overview of his historical, linguistic and pharmaceutical research. He was the first director of the Museum of Natural Sciences and the Library on the History of Pharmaceutics in Budapest is named after him. This was the first monograph of his body of work. In the second two years of my research I have analysed the legacy of Tivadar Acs who was a historian of civilization. His legacy can be found in the Hungarian National Archives and in the Somogyi Library in Szeged. I have compared Acs' manuscripts with his articles in the Hungarian press in the US, complemented them with recent research findings as well as added his unpublished bibliographic notes to his research materials. This was the first comprehensive research of Acs' body of work

Stefan Zweig’s Narratives of Migration and Emigration

Stefan Zweig’s relation to the phenomenon of migration is indeed a complicated issue, which can be approached from at least three perspectives. Firstly, there is the biographic aspect: as one of the major representatives of the German exile literature (Exilliteratur), Zweig has one of the most dramatic biographies among the German authors in the 20th century, including his emigration from Austria to England and New York, then to South America, where (in Petrópolis near Rio de Janeiro) he died in February 1942. Secondly, migration is present in his fictional works, such as the short stories Schachnovelle or Incident on Lake Geneva. Thirdly, Zweig published, a year before his death, his book Brazil, Land of the Future, which, lacking fictitious elements, but including biographic ones, basically summarizes the history (also immigration-history) of Brazil and the main cultural features of his host country. Accordingly, the following paper is a brief analysis of three possible dimensions of migration in Stefan Zweig: biographic migration, including his voluntary and, later, his forced migration, finally fictional migration, i.e. migration as a subject of his works

Supercooling of rapidly expanding quark-gluon plasma

We reexamine the scenario of homogeneous nucleation of the quark-gluon plasma produced in ultra-relativistic heavy ion collisions. A generalization of the standard nucleation theory to rapidly expanding system is proposed. The nucleation rate is derived via the new scaling parameter Z. It is shown that the size distribution of hadronic clusters plays an important role in the dynamics of the phase transition. The longitudinally expanding system is supercooled to about 3 6%, then it is reheated, and the hadronization is completed within 6 10 fm/c, i.e. 5 10 times faster than it was estimated earlier, in a strongly nonequilibrium way. PACS: 12.38.Mh; 12.39.Ba; 25.75.-q; 64.60.Q