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Magnetic anisotropy of thin sputtered MgB2 films on MgO substrates in high magnetic fields
Authors:
Savio Fabretti,
Inga-Mareen Imort,
Timo Kuschel,
Thomas Dahm,
Veerendra K. Guduru,
Uli Zeitler,
Andy Thomas
Abstract:
We investigated the magnetic anisotropy ratio of thin sputtered polycrystalline MgB2 films on MgO substrates. Using high magnetic field measurements, we estimated an anisotropy ratio of 1.35 for T=0 K with an upper critical field of 31.74 T in the parallel case and 23.5 T in the perpendicular case. Direct measurements of a magnetic-field sweep at 4.2 K show a linear behavior, confirmed by a linear…
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We investigated the magnetic anisotropy ratio of thin sputtered polycrystalline MgB2 films on MgO substrates. Using high magnetic field measurements, we estimated an anisotropy ratio of 1.35 for T=0 K with an upper critical field of 31.74 T in the parallel case and 23.5 T in the perpendicular case. Direct measurements of a magnetic-field sweep at 4.2 K show a linear behavior, confirmed by a linear fit for magnetic fields perpendicular to the film plane. Furthermore, we observed a change of up to 12% of the anisotropy ratio in dependence of the film thickness.
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Submitted 12 February, 2014;
originally announced February 2014.
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Anomalous Hall Effect in perpendicularly magnetized Mn(_{3-x})Ga thin films
Authors:
Manuel Glas,
Daniel Ebke,
Inga-Mareen Imort,
Patrick Thomas,
Günter Reiss
Abstract:
Mn$_{3-x}$Ga (x = 0.1, 0.4, 0.7) thin films on MgO and SrTiO$_3$ substrates were investigated with magnetic anisotropy perpendicular to the film plane. An anomalous Hall-effect was observed for the tetragonal distorted lattice in the crystallographic D0$_{22}$ phase. The Hall resistivity $\varrho_{xy}$ was measured in a temperature range from 20 to 330 K. The determined skew scattering and side ju…
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Mn$_{3-x}$Ga (x = 0.1, 0.4, 0.7) thin films on MgO and SrTiO$_3$ substrates were investigated with magnetic anisotropy perpendicular to the film plane. An anomalous Hall-effect was observed for the tetragonal distorted lattice in the crystallographic D0$_{22}$ phase. The Hall resistivity $\varrho_{xy}$ was measured in a temperature range from 20 to 330 K. The determined skew scattering and side jump coefficients are discussed with regard to the film composition and used substrate and compared to the crystallographic and magnetic properties.
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Submitted 17 December, 2012;
originally announced December 2012.
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Local charge and spin currents in magnetothermal landscapes
Authors:
Mathias Weiler,
Matthias Althammer,
Franz D. Czeschka,
Hans Huebl,
Martin S. Wagner,
Matthias Opel,
Inga-Mareen Imort,
Günter Reiss,
Andy Thomas,
Rudolf Gross,
Sebastian T. B. Goennenwein
Abstract:
A scannable laser beam is used to generate local thermal gradients in metallic (Co2FeAl) or insulating (Y3Fe5O12) ferromagnetic thin films. We study the resulting local charge and spin currents that arise due to the anomalous Nernst effect (ANE) and the spin Seebeck effect (SSE), respectively. In the local ANE experiments, we detect the voltage in the Co2FeAl thin film plane as a function of the l…
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A scannable laser beam is used to generate local thermal gradients in metallic (Co2FeAl) or insulating (Y3Fe5O12) ferromagnetic thin films. We study the resulting local charge and spin currents that arise due to the anomalous Nernst effect (ANE) and the spin Seebeck effect (SSE), respectively. In the local ANE experiments, we detect the voltage in the Co2FeAl thin film plane as a function of the laser spot position and external magnetic field magnitude and orientation. The local SSE effect is detected in a similar fashion by exploiting the inverse spin Hall effect in a Pt layer deposited on top of the Y3Fe5O12. Our findings establish local thermal spin and charge current generation as well as spin caloritronic domain imaging.
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Submitted 18 October, 2011;
originally announced October 2011.
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Anomalous Hall effect in the Co-based Heusler compounds Co$_{2}$FeSi and Co$_{2}$FeAl
Authors:
I. -M. Imort,
P. Thomas,
G. Reiss,
A. Thomas
Abstract:
The anomalous Hall effect (AHE) in the Heusler compounds Co$_{2}$FeSi and Co$_{2}$FeAl is studied in dependence of the annealing temperature to achieve a general comprehension of its origin. We have demonstrated that the crystal quality affected by annealing processes is a significant control parameter to tune the electrical resistivity $ρ_{xx}$ as well as the anomalous Hall resistivity $ρ_{ahe}$.…
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The anomalous Hall effect (AHE) in the Heusler compounds Co$_{2}$FeSi and Co$_{2}$FeAl is studied in dependence of the annealing temperature to achieve a general comprehension of its origin. We have demonstrated that the crystal quality affected by annealing processes is a significant control parameter to tune the electrical resistivity $ρ_{xx}$ as well as the anomalous Hall resistivity $ρ_{ahe}$. Analyzing the scaling behavior of $ρ_{ahe}$ in terms of $ρ_{xx}$ points to a temperature-dependent skew scattering as the dominant mechanism in both Heusler compounds.
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Submitted 26 September, 2011;
originally announced September 2011.
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Scaling behavior of the spin pumping effect in ferromagnet/platinum bilayers
Authors:
F. D. Czeschka,
L. Dreher,
M. S. Brandt,
M. Weiler,
M. Althammer,
I. -M. Imort,
G. Reiss,
A. Thomas,
W. Schoch,
W. Limmer,
H. Huebl,
R. Gross,
S. T. B. Goennenwein
Abstract:
We systematically measured the DC voltage V_ISH induced by spin pumping together with the inverse spin Hall effect in ferromagnet/platinum bilayer films. In all our samples, comprising ferromagnetic 3d transition metals, Heusler compounds, ferrite spinel oxides, and magnetic semiconductors, V_ISH invariably has the same polarity. V_ISH furthermore scales with the magnetization precession cone angl…
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We systematically measured the DC voltage V_ISH induced by spin pumping together with the inverse spin Hall effect in ferromagnet/platinum bilayer films. In all our samples, comprising ferromagnetic 3d transition metals, Heusler compounds, ferrite spinel oxides, and magnetic semiconductors, V_ISH invariably has the same polarity. V_ISH furthermore scales with the magnetization precession cone angle with a universal prefactor, irrespective of the magnetic properties, the charge carrier transport mechanism or type. These findings quantitatively corroborate the present theoretical understanding of spin pumping in combination with the inverse spin Hall effect.
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Submitted 29 July, 2011; v1 submitted 14 December, 2010;
originally announced December 2010.
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Magnetic microstructure and magnetotransport in Co2FeAl Heusler compound thin films
Authors:
Mathias Weiler,
Franz D. Czeschka,
Inga-Mareen Imort,
Günter Reiss,
Andy Thomas,
Georg Woltersdorf,
Rudolf Gross,
Sebastian T. B. Goennenwein
Abstract:
We correlate simultaneously recorded magnetotransport and spatially resolved magneto optical Kerr effect (MOKE) data in Co2FeAl Heusler compound thin films micropatterned into Hall bars. Room temperature MOKE images reveal the nucleation and propagation of domains in an externally applied magnetic field and are used to extract a macrospin corresponding to the mean magnetization direction in the Ha…
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We correlate simultaneously recorded magnetotransport and spatially resolved magneto optical Kerr effect (MOKE) data in Co2FeAl Heusler compound thin films micropatterned into Hall bars. Room temperature MOKE images reveal the nucleation and propagation of domains in an externally applied magnetic field and are used to extract a macrospin corresponding to the mean magnetization direction in the Hall bar. The anisotropic magnetoresistance calculated using this macrospin is in excellent agreement with magnetoresistance measurements. This suggests that the magnetotransport in Heusler compounds can be adequately simulated using simple macrospin models, while the magnetoresistance contribution due to domain walls is of negligible importance.
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Submitted 5 November, 2010;
originally announced November 2010.