Open Access. Powered by Scholars. Published by Universities.®
Physical Sciences and Mathematics Commons™
Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 5 of 5
Full-Text Articles in Physical Sciences and Mathematics
Magnetism Of Fept Surface Alloys, Jan Honolka, T. Y. Lee, K. Kuhnke, Axel Enders, Ralph Skomski, S. Bornemann, S. Mankovsky, J. Minar, J. Staunton, H. Ebert, M. Hessler, K. Fauth, G. Schutz, A. Buchsbaum, M. Schmid, P. Varga, K. Kern
Magnetism Of Fept Surface Alloys, Jan Honolka, T. Y. Lee, K. Kuhnke, Axel Enders, Ralph Skomski, S. Bornemann, S. Mankovsky, J. Minar, J. Staunton, H. Ebert, M. Hessler, K. Fauth, G. Schutz, A. Buchsbaum, M. Schmid, P. Varga, K. Kern
Ralph Skomski Publications
The complex correlation of structure and magnetism in highly coercive monoatomic FePt surface alloys is studied using scanning tunneling microscopy, x-ray magnetic circular dichroism, and ab initio theory. Depending on the specific lateral atomic coordination of Fe either hard magnetic properties comparable to that of bulk FePt or complex noncollinear magnetism due to Dzyaloshinski-Moriya interactions are observed. Our calculations confirm the subtle dependence of the magnetic anisotropy and spin alignment on the local coordination and suggest that 3D stacking of Fe and Pt layers in bulk L10 magnets is not essential to achieve high-anisotropy values.
Dzyaloshinski–Moriya Micromagnetics Of Magnetic Surface Alloys, Ralph Skomski, Jan Honolka, S. Bornermann, H. Ebert, Axel Enders
Dzyaloshinski–Moriya Micromagnetics Of Magnetic Surface Alloys, Ralph Skomski, Jan Honolka, S. Bornermann, H. Ebert, Axel Enders
Ralph Skomski Publications
The magnetism of magnetic surface alloys such as Fe–Pt on Pt(997) has been investigated by micromagnetic model calculations. A unique feature of some of these systems is that interatomic exchange, magnetocrystalline anisotropy, and Dzyaloshinski–Moriya (DM) interactions are all of comparable magnitude, of the order of 0.5 meV. This leads to an intriguing nanoscale interplay between ordinary magnetization states and noncollinear spin structures. We identify two cases where the latter dominate. First, for sufficiently strong DM interaction, the zero-field spin structures change from uniform to a canted state with an incommensurate wave vector. Second, a similar transition occurs for weak DM …
Magnetic Correlations In Nanocomposite Fept:Au And Fept:C Films, Thomas A. George, Ralph Skomski, David J. Sellmyer
Magnetic Correlations In Nanocomposite Fept:Au And Fept:C Films, Thomas A. George, Ralph Skomski, David J. Sellmyer
Ralph Skomski Publications
The nanostructure and magnetism of L10-ordered FePt crystallites in matrices of Au and C are investigated as a function of the Au and C contents. Emphasis is on the relation between hysteresis-loop shape, magnetic correlation length, and structural disorder, as relevant to magnetic recording media. The highly (001) textured thin films are produced by annealing [Fe&#;&#;Pt&#;X]n multilayers. The coercivity and the hysteresis-loop slope at coercivity increase and decrease, respectively, with increasing volume fraction of the matrix. The magnetic force microscopy images show that the slope decrease is accompanied by a reduction in the magnetic correlation length. These …
Magnetism Of Tio And Tio2 Nanoclusters, Xiaohui Wei, Ralph Skomski, Balamurugan Balasubramanian, Z. G. Sun, Stephen Ducharme, David J. Sellmyer
Magnetism Of Tio And Tio2 Nanoclusters, Xiaohui Wei, Ralph Skomski, Balamurugan Balasubramanian, Z. G. Sun, Stephen Ducharme, David J. Sellmyer
Ralph Skomski Publications
Nanoclusters of rocksalt TiO, anatase TiO2, and rutile TiO2 were produced by cluster deposition and examined with transmission-electron microscopy, x-ray diffraction, and magnetization measurements. The clusters are all magnetic at room temperature, but the magnetization is structure-dependent. The hysteresis loops show coercivities that are of the order of 100 Oe and all films show a preferential in-plane magnetization direction. The size dependence of the magnetization was investigated for rutile clusters with average sizes from about 15 to 40 nm. The analysis of the measurements indicates that the magnetism is predominantly located near the surface of the clusters …
Graded Permanent Magnets, Ralph Skomski, J. Hadjipanayis, David J. Sellmyer
Graded Permanent Magnets, Ralph Skomski, J. Hadjipanayis, David J. Sellmyer
Ralph Skomski Publications
The effect of semihard magnetic phases and interfaces on the performance of nanostructured two-phase permanent magnets is investigated by model calculations. In addition to the trivial coercivity increase due to the replacement of soft regions by semihard regions, there is a coercivity enhancement even if the volume-averaged anisotropy is kept constant during the introduction of the semihard phase. A variational approach is used to derive analytical results for representative anisotropy profiles. The improvement is operative on length scales slightly larger than that of the soft phase in hard-soft composites, but the main challenge is to find semihard light or heavy …