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Title: Barkhausen noise in variable thickness amorphous finemet films

Abstract

We measured the statistical properties of Barkhausen noise in finemet films with nominal composition Fe{sub 73.5}Cu{sub 1}Nb{sub 3}Si{sub 22.5}B{sub 4} and variable thickness between 25 and 1000 nm. Films have been sputtered on glass substrates and their structure is amorphous. The critical exponents of the power-law distributions for the jumps amplitude show a remarkable stability over the whole thickness range, whereas the other macroscopic magnetic properties undergo strong variations. The value of the critical exponent is about 0.8 between 50 and 500 nm with a small increase up to 1.0 at 1000 nm. These values are similar to those observed with the same experimental technique in other two-dimensional (2D) systems, but definitely smaller with respect to the values observed in truly three-dimensional (3D) systems. Our data therefore indicate that, in the investigated thickness range, the behavior remains typical of 2D systems. The small increase of the critical exponent at 1000 nm might be an indication of a starting transition toward a 3D behavior.

Authors:
; ;  [1]
  1. Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci, 32, I-20132 Milano (Italy)
Publication Date:
OSTI Identifier:
20982764
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 101; Journal Issue: 6; Other Information: DOI: 10.1063/1.2711399; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; BORON ALLOYS; COPPER ALLOYS; DEPOSITION; FERROMAGNETIC MATERIALS; GLASS; IRON ALLOYS; MAGNETIC PROPERTIES; NIOBIUM ALLOYS; SILICON ALLOYS; SUBSTRATES; THICKNESS; THIN FILMS; THREE-DIMENSIONAL CALCULATIONS; TWO-DIMENSIONAL CALCULATIONS

Citation Formats

Puppin, Ezio, Pinotti, Ermanno, and Brenna, Massimiliano. Barkhausen noise in variable thickness amorphous finemet films. United States: N. p., 2007. Web. doi:10.1063/1.2711399.
Puppin, Ezio, Pinotti, Ermanno, & Brenna, Massimiliano. Barkhausen noise in variable thickness amorphous finemet films. United States. doi:10.1063/1.2711399.
Puppin, Ezio, Pinotti, Ermanno, and Brenna, Massimiliano. Thu . "Barkhausen noise in variable thickness amorphous finemet films". United States. doi:10.1063/1.2711399.
@article{osti_20982764,
title = {Barkhausen noise in variable thickness amorphous finemet films},
author = {Puppin, Ezio and Pinotti, Ermanno and Brenna, Massimiliano},
abstractNote = {We measured the statistical properties of Barkhausen noise in finemet films with nominal composition Fe{sub 73.5}Cu{sub 1}Nb{sub 3}Si{sub 22.5}B{sub 4} and variable thickness between 25 and 1000 nm. Films have been sputtered on glass substrates and their structure is amorphous. The critical exponents of the power-law distributions for the jumps amplitude show a remarkable stability over the whole thickness range, whereas the other macroscopic magnetic properties undergo strong variations. The value of the critical exponent is about 0.8 between 50 and 500 nm with a small increase up to 1.0 at 1000 nm. These values are similar to those observed with the same experimental technique in other two-dimensional (2D) systems, but definitely smaller with respect to the values observed in truly three-dimensional (3D) systems. Our data therefore indicate that, in the investigated thickness range, the behavior remains typical of 2D systems. The small increase of the critical exponent at 1000 nm might be an indication of a starting transition toward a 3D behavior.},
doi = {10.1063/1.2711399},
journal = {Journal of Applied Physics},
number = 6,
volume = 101,
place = {United States},
year = {Thu Mar 15 00:00:00 EDT 2007},
month = {Thu Mar 15 00:00:00 EDT 2007}
}
  • Measurements of microwave surface impedance of high-T{sub c} films at gigahertz frequencies and nitrogen temperature are performed. A simple technique employing a parallel-plate resonator with liquid nitrogen as a dielectric spaces is suggested. The use of a precise mechanical device provides smooth changing of distance between films from 200 {mu}m down to zero. Coupling to the resonator is accomplished by means of two small antennas - half-wave vibrators for frequency 10 GHz. The method for determining resistivity and magnetic field penetration depth was based on the analysis of spacer thickness dependences of the resonator quality factor and frequency. YBa{sub 2}Cu{submore » 3}O{sub 7} films produced by a laser deposition technique on CaNdAlO{sub 4} substrates with T{sub c} = 91 K and j{sub c} = 10{sup 7} A/cm{sup 2} and on NdGaO{sub 3} substrates with T{sub c} = 91 K and j{sub c} = 10{sup 6} A/cm{sup 2} are examined, and the values R{sub s} 0.6 m{Omega}, {lambda} = 348 nm at f = 8.97 GHz and R{sub s} = 0.5 m{Omega}, {lambda} = 250 nm at f = 10.12 GHz respectively, are obtained at 77 K. 9 refs., 4 figs.« less
  • Magneto-optical imaging (MO) and electromagnetic studies have been applied to measure anisotropy and critical currents (J{sub c}) of YBa{sub 2}Cu{sub 3}O{sub 7} (YBCO) films with variable thickness of 0.2, 0.5, 1.0, 2.0, and 3.0 {micro}m deposited on flat and vicinal SrTiO{sub 3} substrates of 10 degree miscut angle ({theta}{sub s}). The flat films nucleated in island-type mode and developed with a dominant c-axis orientation with minority misoriented grains at larger thickness of overall dense structure. The vicinal films, on the other hand, nucleated in step-flow mode and developed with a highly porous structure and minimal density of misoriented grains andmore » impurity phases at large thickness. The difference in the microstructures of these two types of films results in different J{sub c} vs. thickness behaviors. The MO images showed that the magnetic flux penetration in the flat samples is isotropic at all thicknesses, while it is highly anisotropic in the vicinal samples. The anisotropy decreases with film thickness and temperature. These results correlate with distinctive patterns of microstructural evolution in flat and vicinal YBCO films with increasing thickness.« less
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  • No abstract prepared.
  • Liquid crystal films are variable thickness, planar targets for ultra-intense laser matter experiments such as ion acceleration. Their target qualities also make them ideal for high-power laser optics such as plasma mirrors and waveplates. By controlling parameters of film formation, thickness can be varied on-demand from 10 nm to above 50 μm, enabling real-time optimization of laser interactions. Presented here are results using a device that draws films from a bulk liquid crystal source volume with any thickness in the aforementioned range. Films form within 2 μm of the same location each time, well within the Rayleigh range of evenmore » tight F/# systems, thus removing the necessity for realignment between shots. As a result, the repetition rate of the device exceeds 0.1 Hz for sub-100nm films, facilitating higher repetition rate operation of modern laser facilities.« less