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Your search keyword '"Sommer, R.L."' showing total 145 results
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145 results on '"Sommer, R.L."'

21. Magnetoimpedance of single and multilayered FeCuNbSiB films in frequencies up to 1.8 GHz

Author

Correa, M.A., Viegas, A.D.C., da Silva, R.B., de Andrade, A.M.H., and Sommer, R.L.

Subjects
Thin films, Multilayered -- Acoustic properties, Nanotechnology -- Research, Copper compounds -- Magnetic properties, Physics
Abstract

A report on very high magnetoimpedance measured at frequencies up to 1.8 GHz in nanostructured [Fe.sub.73.5][Cu.sub.1][Nb.sub.3][Si.sub.13.5][B.sub.9]/Cu film is presented. The results indicate that by playing with the sandwiched and multilayer parameter the response of a magnetoimpedance based sensor could be tuned according to the design needs.

Published
2007

32. Magneto-impedance effects in multilayered permalloy materials

Author

Sommer, R.L., Gundel, A., and Chien, C.L.

Subjects
Magnetism -- Research, Magnetic materials -- Research, Physics
Abstract

The magneto-impedance (MI) effect was investigated in permalloy/Ag multilayers with different Ag thickness and number of bilayer. The magnitude of the MI is substantially increased and the shape of the MI versus H curves transforms from a single-peak centered at H = 0 to a double-peak structure when the Ag thickness is increased from 7 to 25 angstroms. This is due to the different anisotropy axes induced by strain in the multilayers.

Published
1999

35. Magnetization process and magnetoimpedance in (110)(001)FeSi3%

Author

Carara, M., Gundel, A., Baibich, M.N., and Sommer, R.L.

Subjects
Magnetization -- Research, Iron-silicon alloys -- Research, Domain structure -- Research, Physics
Abstract

Research was conducted to examine the magnetoimpedance (MI) effect on (110)(001)FeSi3% and to study the correlation between the magnetic domain structure evolution and the MI along the hysteresis curve for each sample. Based on data obtained at different frequency ranges, the frequency dependence of the effective transverse differential permeability is derived. Results indicate that the MI measurements are a good complementary tool to study the magnetization processes in highly textured materials.

Published
1998

37. Tailoring of magnetocaloric effect in Ni Ni 45.5Mn 43.0In 11.5 metamagnetic shape memory alloy

Author

Rosa, W. O., González-Legarreta, L., García Fernández, Javier, Sánchez, T., Vega, V., Escoda i Acero, Ma. Lluïsa, Suñol Martínez, Joan Josep, Santos, J.D., Alves, M. JP., Sommer, R.L., Prida Pidal, Victor Manuel de la, Hernando, Blanca, and Ministerio de Ciencia e Innovación (Espanya)

Subjects
Condensed Matter::Materials Science, Transition metals -- Alloys, Aliatges, Alloys, Metalls de transició -- Aliatges
Abstract

We investigate the direct and inverse magnetocaloric effect in Ni 45.5Mn 43.0In 11.5 Heusler alloy ribbons comparing the results obtained for the as-quenched sample with the ones after different annealing procedures. An enhancement and shift of the entropy maximum to near room temperature is observed in all annealed samples. A remarkable magnetocaloric effect is observed in samples with short-time treatment (10 minutes) and at the lowest annealing temperature. We show that the suppressing of uncompensated martensitic transition and thermal hysteresis are both influenced by the heat treatment. Also, an improvement on Curie's temperature is observed and, at low magnetic field, it has been risen up to 310K. Our results demonstrate that the martensitic transformation is highly sensitive to the applied magnetic field and also to the annealing treatment, which means that the magnetocaloric effect can be tuned showing different behaviors for each sample Authors are thankful to Spanish MICINN for financial support: MAT2009-13108-C02-01-02 and MAT2010-20798-C05-04

Published
2018

42. Dynamic hysteresis in finemet thin films

Author

Santi, L., Sommer, R.L., Magni, A., Durin, G., Colaiori, F., and Zapperi, S.

Subjects
Electromagnetism -- Research, Thin films -- Research, Dielectric films -- Research, Business, Electronics, Electronics and electrical industries
Abstract

We performed a series of dynamic hysteresis measurements on Finemet films with composition [Fe.sub.73.5][Cu.sub.1][Nb.sub.3][Si.sub.13.5][B.sub.9], using both the longitudinal magneto-optical Kerr effect (MOKE) and the inductive fluxometric method. The MOKE dynamic hysteresis loops show a more marked variability with the frequency than the inductive ones, while both measurements show a similar dependence on the square root of frequency. We analyze these results in the frame of a simple domain wall depinning model, which accounts for the general behavior of the data. Index Terms--Domain wall dynamics, dynamic hysteresis, magnetic thin films, magnetization processes.

Published
2003

43. Stress level in Finemet materials studied by impedanciometry

Author

Carara, Marcos, Baibich, M.N., and Sommer, R.L.

Subjects
Annealing -- Analysis, Copper -- Thermal properties, Iron compounds -- Thermal properties, Impedance (Electricity) -- Research, Physics
Abstract

The stress relief in Finemet ribbons Fe73.5Cu1Nb3Si16.5B6 as a function of the annealing temperature is discussed. The comparison of the as-cast to the sample annealed at 580 degree C verifies the reduction in the internal stress from 15 to 0.2 MPa.

Published
2002

44. Barkhausen noise measurements in materials with vanishing magnetoelastic anisotropies

Author

Santi, L., Denardin, J.C., Dotto, M.R., Schelp, L.F., and Sommer, R.L.

Subjects
Physics -- Research, Copper compounds -- Magnetic properties, Iron compounds -- Magnetic properties, Physics
Abstract

The Barkhausen noise measurements performed on amorphous ribbons Metglas 2605TCA (Fe based), Metglas 2705M (Co based) and Finemet materials with composition Fe73.5Cu1Nb3Si18.5B4 are discussed. The power spectra were found to be sensitive for low stress levels (Fe-based Metglas) and for annealing temperature above 300 degree C.

Published
2002

45. Tunnel magnetoresistance in NiFe/TaO(sub x)/Al2O3/Co junctions with a thin TaO(sub x) layer

Author

Dorneles, L.S., Sommer, R.L., and Schelp, L.F.

Subjects
Nickel compounds -- Magnetic properties, Titanium compounds -- Magnetic properties, Aluminum oxide -- Magnetic properties, Magnetoresistance -- Analysis, Physics
Abstract

The magnetoresistance versus bias voltage in NiFe/TaO(sub x)/Al2O3/Co magnetic tunnel junctions is measured. A faster decline of magnetoresistance is observed in samples with 0.5 nm of Ta with the increase in bias voltage.

Published
2002

48. Magnetic and magneto-transport properties of metastable Gd(sub x)Nb(sub 1-x) alloys

Author

Sommer, R.L., Xiao, John Q., and Chien, C.L.

Subjects
Gadolinium -- Research, Niobium -- Research, Rare earth metals -- Magnetic properties, Magnetization -- Research, Business, Electronics, Electronics and electrical industries
Abstract

Metastable [Gd.sub.x][Nb.sub.1-x] alloys over the entire composition range have been realized by co-deposition at room temperature. Structural and magnetic phase diagrams have been determined. The alloys are crystalline bcc (0.00 [less than or equal to] x < 0.40), amorphous (0.40 [less than or equal to] x [less than or equal to] 0.70), and crystalline hcp (0.70 [less than or equal to] x [less than or equal to] 1.00). Magnetic and magneto-transport measurements show spin glass ordering for x [less than or equal to] 0.60, and ferromagnetic ordering with a weak spin glass transition for x > 0.60. Index Terms - Matastable Gd-Nb alloys, magneto.transport, magnetism, rare-earths.

Published
1998

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