Browsing by Author "Schreyer, A"
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- ItemAntiferromagnetism in a Fe50Pt40Rh10 thin film investigated using neutron diffraction(American Physical Society, 2008-11) Lott, D; Fenske, J; Schreyer, A; Mani, P; Mankey, GJ; Klose, F; Schmidt, W; Schmalzl, K; Tartakovskaya, EVThe temperature-dependent magnetic structure of a 200 nm thick single-crystalline film of Fe50Pt40Rh10 was studied by unpolarized and polarized neutron diffractions. By applying structure factor calculations, a detailed model of the magnetic unit cell was developed. In contrast to former studies on bulk samples, our experimental results show that the film remains in an antiferromagnetic state throughout the temperature range of 10–450 K. Remarkably, it can be demonstrated that the antiferromagnetic structure undergoes a smooth transition from a dominant out-of-plane order with the magnetic moments orientated in-plane to an in-plane order with the magnetic moments orientated perpendicular to the film plane. Theoretically this can be explained by the existence of two competing anisotropy contributions with different temperature dependencies. © 2008, American Physical Society
- ItemArtificially modulated chemical order in thin films: a different approach to create ferro/antiferromagnetic interfaces(American Physical Society, 2010-10-06) Saerbeck, T; Klose, F; Lott, D; Mankey, GJ; Lu, Z; LeClair, PR; Schmidt, W; Stampfl, APJ; Danilkin, SA; Yethiraj, M; Schreyer, AWe report on a unique magnetic exchange interaction in a thin film of FePt3, comprising an artificially created ferromagnetic (FM)/antiferromagnetic (AFM) modulation, but homogeneous chemical composition and epitaxy throughout the film. The chemical order, on the other hand, is modulated resulting in the formation of alternating FM/AFM layers. To determine the existence and form of the magnetic structure within the monostoichiometric thin film, we use a unique combination of polarized neutron reflectometry, x-ray/neutron diffraction, and conventional magnetometry. This artificial stratified AFM/FM FePt3 exhibits a high magnetic exchange bias thus opening up possibilities to study such magnetic phenomena in a perfectly lattice-matched system. © 2010, American Physical Society
- ItemChemical-order-induced magnetic exchange bias in epitaxial FePt3 films(American Physical Society, 2008-04-11) Lott, D; Klose, F; Ambaye, H; Mankey, GJ; Mani, P; Wolff, M; Schreyer, A; Christen, HM; Sales, BCWe show that magnetic exchange bias can be induced by means of chemical ordering. The effect was observed on epitaxial thin film layers of FePt3, a material which has the remarkable property that, depending on the degree of chemical order, a ferromagnetic and an antiferromagnetic magnetic state can coexist at the same temperature. We demonstrate that the observed exchange bias originates at the interfaces between these two different magnetic phases of FePt3. © 2008, American Physical Society
- ItemThe instrument suite of the European Spallation Source(Elsevier B. V., 2020-01-10) Andersen, KH; Argyriou, DN; Jackson, AJ; Houston, J; Henry, PF; Deen, PP; Toft-Petersen, R; Beran, P; Strobl, M; Arnold, T; Wacklin-Knecht, H; Vivanco, R; Parker, SF; Gussen, A; Kanaki, K; Scionti, G; Olsen, MA; Arai, M; Schmakat, Ph; Lechner, RE; Niedermayer, Ch; Schneider, H; Zanetti, M; Petrillo, C; Moreira, FY; Stepanyan, S; Luna, P; Calzada, E; Stahn, J; Voigt, J; Dupont, T; Hanslik, R; Siemers, DJ; Udby, L; Chowdhury, MAH; Klauser, Ch; Rouijaa, M; Lehmann, E; Heynen, A; Bustinduy, I; Schwaab, A; Raspino, D; Scatigno, C; del Moral, OG; Kiehn, R; Aprigliano, G; Zanatta, M; Huerta, M; Bellissima, S; Lerche, M; Holm-Dahlin, S; Huerta, M; Christensen, NB; Lohstroh, W; Gorini, G; Fenske, J; Hansen, UB; Klauser, C; Rodrigues, S; Müller, M; Gorini, G; Bovo, C; Hall-Wilton, R; Fabrèges, X; Siemers, DJ; Khaplanov, A; Tsapatsaris, N; Taylor, J; Christensen, M; Schefer, J; Woracek, R; Tozzi, P; Müller, M; Carlsen, H; Olsen, MA; Orecchini, A; Di Fresco, L; Paciaroni, A; Bovo, C; Magán, M; Hauback, BC; Elmer, J; Heenan, RK; Piscitelli, F; Masi, F; Bakedano, G; Klimko, S; De Bonis, A; Fedrigo, A; Lukáš, P; Frielinghaus, H; Stahn, J; Schweika, W; Markó, M; Pfeiffer, D; Kirstein, O; Di Fresco, L; Schreyer, A; Orszulik, A; Nowak, G; Butterweck, S; Šaroun, J; Paciaroni, A; Kolevatov, R; Lehmann, EH; Filges, U; Schreyer, A; Koenen, M; Bustinduy, I; Magán, M; Feygenson, M; Cooper, JFK; Abad, E; Senesi, R; Longeville, S; Llamas-Jansa, I; Schulz, M; Birk, JO; Sharp, M; Galsworthy, P; Šaroun, J; Martínez, J; Hiess, A; Holm-Dahlin, S; Filges, U; Pullen, SA; Guyon Le Bouffy, J; Schefer, J; Lukáš, P; Udby, L; Kozielewski, T; Niedermayer, C; Sacchetti, F; Hartl, M; Jaksch, S; Salhi, Z; Brückel, T; Aguilar, J; Aguilar, J; Seifert, M; Bordallo, HN; Robillard, T; Villacorta, FJ; Herranz, I; del Rosso, L; Hauback, BC; Orecchini, A; Fabrèges, G; Fenske, J; Neuhaus, J; Schillinger, B; Abad, E; Kittelmann, T; Lefmann, K; Seifert, M; Neuhaus, J; Herranz, I; Kolevatov, R; Annighöfer, B; Oksanen, E; Morgano, M; Laszlo, G; Freeman, PG; Kennedy, SJ; Bertelsen, M; Bellissima, S; Alba-Simionesco, C; Markó, M; Mezei, F; Chowdhury, M; Halcrow, W; Jestin, J; Lieutenant, K; Babcock, E; Rønnow, HM; Engels, R; del Moral, OG; Vickery, A; Rouijaa, M; Lavie, P; Petersson Årsköld, S; Glavic, A; Désert, S; Mannix, D; Scatigno, C; Petry, W; Christensen, NB; Violini, N; Villacorta, FJ; Porcher, F; Glavic, A; Scionti, G; Zanetti, M; Fernandez-Alonso, F; Rønnow, HM; Mosconi, M; Olsson, M; Stepanyan, S; Petrillo, C; del Rosso, L; Harbott, P; Sacchetti, F; Bertelsen, M; Kämmerling, H; Andreani, C; Schulz, M; Colognesi, D; Luna, P; Loaiza, L; Turner, D; Martínez, JL; Tartaglione, A; Sordo, F; Llamas-Jansa, I; Schmakat, P; Lechner, RE; Poqué, A; Fernandez-Alonso, F; Colognesi, D; Tartaglione, A; Morgano, M; Webb, N; Loaiza, L; Whitelegg, L; Petry, W; Iversen, K; Vivanco, R; Tozzi, P; Goukassov, A; Schillinger, B; Carlsen, H; Masi, F; Christensen, M; Nowak, G; Nightingale, J; Schütz, S; Lopez, CI; Langridge, S; Schütz, S; Nagy, G; Zanatta, M; Andreani, C; Lefmann, K; Lohstroh, W; Mosconi, M; Senesi, R; Stefanescu, I; Bakedano, G; Hagen, ME; Wischnewski, A; Bourges, P; Hansen, UB; De Bonis, A; Kiehn, R; Parker, SF; Iversen, K; Sordo, F; Freeman, PG; Birk, JO; Rodríguez, DM; Ansell, SAn overview is provided of the 15 neutron beam instruments making up the initial instrument suite of the European Spallation Source (ESS), and being made available to the neutron user community. The ESS neutron source consists of a high-power accelerator and target station, providing a unique long-pulse time structure of slow neutrons. The design considerations behind the time structure, moderator geometry and instrument layout are presented. The 15-instrument suite consists of two small-angle instruments, two reflectometers, an imaging beamline, two single-crystal diffractometers; one for macromolecular crystallography and one for magnetism, two powder diffractometers, and an engineering diffractometer, as well as an array of five inelastic instruments comprising two chopper spectrometers, an inverse-geometry single-crystal excitations spectrometer, an instrument for vibrational spectroscopy and a high-resolution backscattering spectrometer. The conceptual design, performance and scientific drivers of each of these instruments are described. All of the instruments are designed to provide breakthrough new scientific capability, not currently available at existing facilities, building on the inherent strengths of the ESS long-pulse neutron source of high flux, flexible resolution and large bandwidth. Each of them is predicted to provide world-leading performance at an accelerator power of 2 MW. This technical capability translates into a very broad range of scientific capabilities. The composition of the instrument suite has been chosen to maximise the breadth and depth of the scientific impact of the early years of the ESS, and provide a solid base for completion and further expansion of the facility. © 2020 The Authors. Published by Elsevier B.V. Open access article under the CC BY-NC-ND license.
- ItemA new approach to the creation of magnetically modulated structures(Australian Institute of Physics, 2010-02-03) Saerbeck, T; Klose, F; Lott, D; Mankey, GJ; Lu, Z; LeClair, PR; Stampfl, APJ; Danilkin, SA; Yethiraj, M; Schreyer, AThe plethora of structural and magnetic properties observed in many transition metal alloys has attracted a great deal of interest in both the pure and applied sciences [1]. One key attribute of these alloys is that their electronic and magnetic properties are extremely sensitive to not only stoichiometry but order as well. In this paper we report on a new approach of creating a magnetically modulated structure, without changing composition or lattice structure, namely by artificially controlling the degree of chemical order in the material. The compound FePt3, as it is well known from bulk crystals, has the extraordinary property to evolve ferromagnetic (FM) or antiferromagnetic (AFM) phases determined by the degree of chemical ordering [2]. We succeeded in preparing epitaxial FePt3 superlattices of homogeneous composition consisting of an artificially modulated ferro/antiferromagnetic layering sequence simply by alternating the growth temperature. A direct effect of such an exotic FM/AFM interface is the observation of a high exchange bias upon field cooling through the Nèel temperature. In order to quantify the degree of antiferromagnetic ordering, high angle neutron diffraction has been performed using the triple axis spectrometer IN12 (Institute Laue Langevin, Grenoble) and TAIPAN (Australian Nuclear Science and Technology Organisation). Similar to chemically ordered bulk FePt3 the superlattice exhibits the onset of a (½ ½ 0) AFM Bragg peak below a temperature of TN=140 K (Bulk TN=160 K [2]). Using the polarized neutron reflectometry technique at the German research facility GKSS, Geesthacht, a detailed layer resolved magnetic characterization of the superlattice was carried out.
- ItemStructural and magnetic properties of epitaxial Fe25Pt75(American Vacuum Society, 2009-07) Lu, Z; Walock, MJ; LeClair, PR; Mankey, GJ; Mani, P; Lott, D; Klose, F; Ambaye, H; Lauter, V; Wolff, M; Schreyer, A; Christen, HM; Sales, BCEpitaxial films of Fe25Pt75 have a number of different magnetic phases as a function of temperature and chemical order. For example, chemically ordered epitaxial films have two distinct antiferromagnetic phases at temperatures below similar to 160 K and exhibit paramagnetism above that temperature. In sharp contrast, chemically disordered epitaxial films are ferromagnetic with a Curie temperature that is greater than 400 K. It is demonstrated that by varying the substrate temperature during growth, epitaxial films with varying degrees of chemical order can be produced and it is possible to produce an alloy with the same composition throughout the film with a modified magnetic structure. The authors used polarized neutron reflectivity to gauge the magnetism of a Fe25Pt75 sample produced with a periodic variation in the growth temperature and showed that the sample exhibits a reduced Curie temperature of approximately 300 K as compared to bulk Fe25Pt75. © 2009, American Vacuum Society