H. Hurdequint - Academia.edu (original) (raw)
Papers by H. Hurdequint
HAL (Le Centre pour la Communication Scientifique Directe), Nov 24, 2021
The spectral signatures of magnetic skyrmions under microwave field excitation are of fundamental... more The spectral signatures of magnetic skyrmions under microwave field excitation are of fundamental interest and can be an asset for high frequency applications. These topological solitons can be tailored in multilayered thin films, but the experimental observation of their spin wave dynamics remains elusive, in particular due to large damping. Here, we study Pt/FeCoB/AlO x multilayers hosting dense and robust skyrmion lattices at room temperature with Gilbert damping of ∼ 0.02. We use magnetic force microscopy to characterise their static magnetic phases and broadband ferromagnetic resonance to probe their high frequency response. Micromagnetic simulations reproduce the experiments with accuracy and allow us to identify distinct resonant modes detected in the skyrmion lattice phase. Low (< 2 GHz) and intermediate frequency (2−8 GHz) modes involve excitations localised to skyrmion edges in conjunction with precession of the uniform background magnetisation, while a high frequency (> 12 GHz) mode corresponds to in-phase skyrmion core precession emitting spin waves into uniform background with wavelengths in the 50-80 nm range commensurate with the lattice structure. These findings could be instrumental in the investigation of room temperature wave scattering and the implementation of novel microwave processing schemes in reconfigurable arrays of solitons.
Journal of Applied Physics, 1991
We report a detailed ferromagnetic resonance (FMR) study, at X band, of magnetic films constitute... more We report a detailed ferromagnetic resonance (FMR) study, at X band, of magnetic films constituted of (Ag&amp;Verbar;Fe multilayer&amp;Verbar;Ag) sandwiches deposited by sputtering on heated mica substrates, where the base and the top Ag layers are 550 A˚ thick. For this (Ag/Fe) system the corresponding series of single Fe layers is reported in Ref. 1 (structural characteristics, FMR study). The resonance
Physics, Fabrication, and Applications of Multilayered Structures, 1988
Physical Review B, 2008
We review how a magnetic resonance force microscope (MRFM) can be applied to perform ferromagneti... more We review how a magnetic resonance force microscope (MRFM) can be applied to perform ferromagnetic resonance (FMR) spectroscopy of individual sub-micron size samples. We restrict our attention to a thorough study of the spin-wave eigen-modes excited in permalloy (Py) disks patterned out of the same 43.3 nm thin film. The disks have a diameter of either 1.0 or 0.5 µm and are quasi-saturated by a perpendicularly applied magnetic field. It is shown that quantitative spectroscopic information can be extracted from the MRFM measurements. In particular, the data are extensively compared with complementary approximate models of the dynamical susceptibility: i) a 2D analytical model, which assumes an homogeneous magnetization dynamics along the thickness and ii) a full 3D micromagnetic simulation, which assumes an homogeneous magnetization dynamics below a characteristic length scale c and which approximates the cylindrical sample volume by a discretized representation with regular cubic mesh of lateral size c = 3.9 nm. In our analysis, the distortions due to a breaking of the axial symmetry are taken into account, both models incorporating the possibility of a small misalignment between the applied field and the normal of the disks.
Journal of Magnetism and Magnetic Materials, 2004
An improved broadband inductive technique for the measurement of magnetization dynamics in thin f... more An improved broadband inductive technique for the measurement of magnetization dynamics in thin ferromagnetic films is presented. The technique is demonstrated using 9:3 nm thick Permalloy films, and allows for time and frequency domain measurements to be made in parallel. Free oscillations after short duration pulses ð200 psÞ and broadband response to radio frequency fields up to 6 GHz have been observed, and can be precisely matched to existing theories.
Journal of Applied Physics, 1991
Abstract The FMR spectrum, at X band and room temperature, of (Ag|single Fe layer|Ag) sandwiches ... more Abstract The FMR spectrum, at X band and room temperature, of (Ag|single Fe layer|Ag) sandwiches deposited on mica is studied as a function of the dc applied field orientation. It is deduced, from the thickness dependence of the anisotropy of ultrathin Fe layers, that the interface-induced anisotropy characteristic of the (Ag|Fe) interface is essentially an easy axis perpendicular anisotropy whose effective value of the anisotropy constant is consistent with the one determined from the field position of a surface mode observed in thick Fe layers.
Physical Review Letters, 2009
Journal of Applied Physics, 1985
We have carried out an electron spin resonance (ESR) study of a disordered Ni–Mn alloy of 26.5 at... more We have carried out an electron spin resonance (ESR) study of a disordered Ni–Mn alloy of 26.5 at. &amp;percnt; Mn at 9.2 GHz. Investigated in particular was the variation of the resonance spectrum as a function of the orientation of the static magnetic field relative to the plane of the thin-foil sample. The measurements were made at different temperatures and
Physical review. B, Condensed matter, 1986
Ferromagnetic resonance measurements in Co films of 11.3, 20, and 80 A&amp;amp;amp;amp;am... more Ferromagnetic resonance measurements in Co films of 11.3, 20, and 80 A&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#778 thickness sandwiched by Au have been made as a function of the dc magnetic field orientation in a plane perpendicular to the film. These polycrystalline films were measured to have the hcp structure with the c axis perpendicular to the film plane within a few degrees. The experimental
E.S.R. measurements have been carried out on a single crystal of ~(BEDT-TTF)2I 3 where, successiv... more E.S.R. measurements have been carried out on a single crystal of ~(BEDT-TTF)2I 3 where, successively, the ~H and ~L phases were studied. These phases are essentially characterized by different linewidths at low temperatures. In a large temperature range the spin susceptibility is nearly temperature independent and takes nearly the same values in both phases suggesting that the difference in superconducting T is not to be accounted for by different values of the density c of states at the Fermi level. Anisotropy effects revealed at low temperature, for both phases, in the angular variation of the ESR signal (lineshape and intensity)are likely to be linked to the marked 2 D anisotropy of the conductivity of this material. pressure (% 1 kbar) down to 77 K or so and a subsequent cooling performed at ambient pressure allows the stabilization of another phase of the compound (~-H phase) exhibiting superconductivity below T = 8.1 K [i]. The possibility c of two, so different, superconducting states in (BEDT-TTF) 2I 3 is a unique feature among organic superconductors. Therefore we have felt concerned about understanding such a phenomenon and in particular the magnitude and temperature dependence of the spin susceptibility, in both the ~-L and ~-H phases, as may be derived from the E.S.R. signal intensity.
Le Journal De Physique Colloques, 1988
![Research paper thumbnail of Pressure-temperature phase diagram of α′-TTF [Pd(Dmit)2]2](https://attachments.academia-assets.com/80656190/thumbnails/1.jpg)
](Synthetic Metals, 1988
Temperature dependence of resistivity (up to 24 Kbar) and of E.S.R.(at I bar) measurements sugges... more Temperature dependence of resistivity (up to 24 Kbar) and of E.S.R.(at I bar) measurements suggest that centered monoclinic TTF[Pd(Dmit) 2] 2 could be an anisotropic and weak antiferromagnetie fluctuating metal. At low pressure, gradual charge and spin localizations at different temperatures are the signature of a Mott-Hubbard insulator. Above 20 Kbar, "high" superconducting onset temperatures (6.5 K) are observed. also with 2~/b, where b is the unit cell parameter along the stack direction of the centered monoclinic structure. Thus, if any 2k i (i = D,AI or A2) modulation wave appears with decreasing temperature, the Fermi surface should disappear on the corresponding chain but not on the two other ones and metallic behaviour would still remain. But despite this elegant approach, it has to be pointed out that
Physical Review Letters, 1972
Journal of Magnetism and Magnetic Materials, 2007
Results of FMR studies performed at X-band on two series of thin permalloy (Py) layers sandwiched... more Results of FMR studies performed at X-band on two series of thin permalloy (Py) layers sandwiched by Au are reported and analyzed. These two series are characterized by an Au layer thickness of 12 and 6 nm, respectively. The FMR results are compared to the ones obtained for a series of (Py/Al 2 O 3) control films. A strong interfacial increase of the intrinsic damping is revealed. The spin-orbit perpendicular anisotropy field is also dominated by the metallic interface contribution. Remarkable phenomena evidenced in the angular variation of the FMR spectrum may be well understood in terms of the theoretical description we have developed of the observable signal in a bimetallic (ferro/normal) film.
Journal of Magnetism and Magnetic Materials, 2002
We report and analyze the results of detailed FMR studies performed on films corresponding to per... more We report and analyze the results of detailed FMR studies performed on films corresponding to permalloy ultrathin layers sandwiched by Al2O3. It is shown that calculations based on a theoretical description of the inhomogeneous linewidth, including the effect of exchange narrowing, enable to reproduce rather well the magnitude and angular variation of the observed width.
Le Journal De Physique Colloques, 1988
FMR results, at E band and X band, were obtained for an iron layer (sandviriched by Ag and deposi... more FMR results, at E band and X band, were obtained for an iron layer (sandviriched by Ag and deposited on mica and bulk silver substrates), TESR measurements being also performed for the silver sample. Various effects induced by the coupling at the (Fe/Ag) interface are evidenced in the spectra and are to be dominantly associated to the diffusion of the conduction electron magnetization.
Journal of Magnetism and Magnetic Materials, 1991
The FMR spectrum, at X band and room temperature, is studied as a function of the dc field orient... more The FMR spectrum, at X band and room temperature, is studied as a function of the dc field orientation for a series of films constituted of (AgIFe bilayer]Ag) sandwiches where the Fe bilayers (FellAglFe2) have the same Fe layer thickness (36A) but a Ag spacer thickness varied in a large range. All the resonance characteristics of these Fe bilayers, when compared to the ones of a Fe single layer control sample, provide evidence for dynamic coupling effects between the two Fe layers which, we suggest, are to be associated with the diffusion of the conduction electron magnetization through the Ag spacer.
Journal of Magnetism and Magnetic Materials, 1982
Magnetic measurements reveal that the alloy Ni78Mn22 undergoes a field-induced spin-glass-to-ferr... more Magnetic measurements reveal that the alloy Ni78Mn22 undergoes a field-induced spin-glass-to-ferromagnetic transition at a critical field that decreases from ~ 140 Oe to zero as the temperature is raised from 4.2 to 40 K, its ferromagnetic Curie point being ~ 270 K. The alloy Ni74Mn26 is found to have a related state of infinite initial susceptibility but no spontaneous magnetization
Journal of Magnetism and Magnetic Materials, 1983
ESR spectra were obtained for disordered Ni74Mn26 cooled to ~ 4K in zero field and 10 kOe. The re... more ESR spectra were obtained for disordered Ni74Mn26 cooled to ~ 4K in zero field and 10 kOe. The resonance observed after field-cooling are asymmetric with the applied field direction up to ~ 30 K and continue to show a macroscopic anisotropy field up to ~ K, where a transition occurs from spin-glass to ferromagnetism.
HAL (Le Centre pour la Communication Scientifique Directe), Nov 24, 2021
The spectral signatures of magnetic skyrmions under microwave field excitation are of fundamental... more The spectral signatures of magnetic skyrmions under microwave field excitation are of fundamental interest and can be an asset for high frequency applications. These topological solitons can be tailored in multilayered thin films, but the experimental observation of their spin wave dynamics remains elusive, in particular due to large damping. Here, we study Pt/FeCoB/AlO x multilayers hosting dense and robust skyrmion lattices at room temperature with Gilbert damping of ∼ 0.02. We use magnetic force microscopy to characterise their static magnetic phases and broadband ferromagnetic resonance to probe their high frequency response. Micromagnetic simulations reproduce the experiments with accuracy and allow us to identify distinct resonant modes detected in the skyrmion lattice phase. Low (< 2 GHz) and intermediate frequency (2−8 GHz) modes involve excitations localised to skyrmion edges in conjunction with precession of the uniform background magnetisation, while a high frequency (> 12 GHz) mode corresponds to in-phase skyrmion core precession emitting spin waves into uniform background with wavelengths in the 50-80 nm range commensurate with the lattice structure. These findings could be instrumental in the investigation of room temperature wave scattering and the implementation of novel microwave processing schemes in reconfigurable arrays of solitons.
Journal of Applied Physics, 1991
We report a detailed ferromagnetic resonance (FMR) study, at X band, of magnetic films constitute... more We report a detailed ferromagnetic resonance (FMR) study, at X band, of magnetic films constituted of (Ag&amp;Verbar;Fe multilayer&amp;Verbar;Ag) sandwiches deposited by sputtering on heated mica substrates, where the base and the top Ag layers are 550 A˚ thick. For this (Ag/Fe) system the corresponding series of single Fe layers is reported in Ref. 1 (structural characteristics, FMR study). The resonance
Physics, Fabrication, and Applications of Multilayered Structures, 1988
Physical Review B, 2008
We review how a magnetic resonance force microscope (MRFM) can be applied to perform ferromagneti... more We review how a magnetic resonance force microscope (MRFM) can be applied to perform ferromagnetic resonance (FMR) spectroscopy of individual sub-micron size samples. We restrict our attention to a thorough study of the spin-wave eigen-modes excited in permalloy (Py) disks patterned out of the same 43.3 nm thin film. The disks have a diameter of either 1.0 or 0.5 µm and are quasi-saturated by a perpendicularly applied magnetic field. It is shown that quantitative spectroscopic information can be extracted from the MRFM measurements. In particular, the data are extensively compared with complementary approximate models of the dynamical susceptibility: i) a 2D analytical model, which assumes an homogeneous magnetization dynamics along the thickness and ii) a full 3D micromagnetic simulation, which assumes an homogeneous magnetization dynamics below a characteristic length scale c and which approximates the cylindrical sample volume by a discretized representation with regular cubic mesh of lateral size c = 3.9 nm. In our analysis, the distortions due to a breaking of the axial symmetry are taken into account, both models incorporating the possibility of a small misalignment between the applied field and the normal of the disks.
Journal of Magnetism and Magnetic Materials, 2004
An improved broadband inductive technique for the measurement of magnetization dynamics in thin f... more An improved broadband inductive technique for the measurement of magnetization dynamics in thin ferromagnetic films is presented. The technique is demonstrated using 9:3 nm thick Permalloy films, and allows for time and frequency domain measurements to be made in parallel. Free oscillations after short duration pulses ð200 psÞ and broadband response to radio frequency fields up to 6 GHz have been observed, and can be precisely matched to existing theories.
Journal of Applied Physics, 1991
Abstract The FMR spectrum, at X band and room temperature, of (Ag|single Fe layer|Ag) sandwiches ... more Abstract The FMR spectrum, at X band and room temperature, of (Ag|single Fe layer|Ag) sandwiches deposited on mica is studied as a function of the dc applied field orientation. It is deduced, from the thickness dependence of the anisotropy of ultrathin Fe layers, that the interface-induced anisotropy characteristic of the (Ag|Fe) interface is essentially an easy axis perpendicular anisotropy whose effective value of the anisotropy constant is consistent with the one determined from the field position of a surface mode observed in thick Fe layers.
Physical Review Letters, 2009
Journal of Applied Physics, 1985
We have carried out an electron spin resonance (ESR) study of a disordered Ni–Mn alloy of 26.5 at... more We have carried out an electron spin resonance (ESR) study of a disordered Ni–Mn alloy of 26.5 at. &amp;percnt; Mn at 9.2 GHz. Investigated in particular was the variation of the resonance spectrum as a function of the orientation of the static magnetic field relative to the plane of the thin-foil sample. The measurements were made at different temperatures and
Physical review. B, Condensed matter, 1986
Ferromagnetic resonance measurements in Co films of 11.3, 20, and 80 A&amp;amp;amp;amp;am... more Ferromagnetic resonance measurements in Co films of 11.3, 20, and 80 A&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#778 thickness sandwiched by Au have been made as a function of the dc magnetic field orientation in a plane perpendicular to the film. These polycrystalline films were measured to have the hcp structure with the c axis perpendicular to the film plane within a few degrees. The experimental
E.S.R. measurements have been carried out on a single crystal of ~(BEDT-TTF)2I 3 where, successiv... more E.S.R. measurements have been carried out on a single crystal of ~(BEDT-TTF)2I 3 where, successively, the ~H and ~L phases were studied. These phases are essentially characterized by different linewidths at low temperatures. In a large temperature range the spin susceptibility is nearly temperature independent and takes nearly the same values in both phases suggesting that the difference in superconducting T is not to be accounted for by different values of the density c of states at the Fermi level. Anisotropy effects revealed at low temperature, for both phases, in the angular variation of the ESR signal (lineshape and intensity)are likely to be linked to the marked 2 D anisotropy of the conductivity of this material. pressure (% 1 kbar) down to 77 K or so and a subsequent cooling performed at ambient pressure allows the stabilization of another phase of the compound (~-H phase) exhibiting superconductivity below T = 8.1 K [i]. The possibility c of two, so different, superconducting states in (BEDT-TTF) 2I 3 is a unique feature among organic superconductors. Therefore we have felt concerned about understanding such a phenomenon and in particular the magnitude and temperature dependence of the spin susceptibility, in both the ~-L and ~-H phases, as may be derived from the E.S.R. signal intensity.
Le Journal De Physique Colloques, 1988
Synthetic Metals, 1988
Temperature dependence of resistivity (up to 24 Kbar) and of E.S.R.(at I bar) measurements sugges... more Temperature dependence of resistivity (up to 24 Kbar) and of E.S.R.(at I bar) measurements suggest that centered monoclinic TTF[Pd(Dmit) 2] 2 could be an anisotropic and weak antiferromagnetie fluctuating metal. At low pressure, gradual charge and spin localizations at different temperatures are the signature of a Mott-Hubbard insulator. Above 20 Kbar, "high" superconducting onset temperatures (6.5 K) are observed. also with 2~/b, where b is the unit cell parameter along the stack direction of the centered monoclinic structure. Thus, if any 2k i (i = D,AI or A2) modulation wave appears with decreasing temperature, the Fermi surface should disappear on the corresponding chain but not on the two other ones and metallic behaviour would still remain. But despite this elegant approach, it has to be pointed out that
Physical Review Letters, 1972
Journal of Magnetism and Magnetic Materials, 2007
Results of FMR studies performed at X-band on two series of thin permalloy (Py) layers sandwiched... more Results of FMR studies performed at X-band on two series of thin permalloy (Py) layers sandwiched by Au are reported and analyzed. These two series are characterized by an Au layer thickness of 12 and 6 nm, respectively. The FMR results are compared to the ones obtained for a series of (Py/Al 2 O 3) control films. A strong interfacial increase of the intrinsic damping is revealed. The spin-orbit perpendicular anisotropy field is also dominated by the metallic interface contribution. Remarkable phenomena evidenced in the angular variation of the FMR spectrum may be well understood in terms of the theoretical description we have developed of the observable signal in a bimetallic (ferro/normal) film.
Journal of Magnetism and Magnetic Materials, 2002
We report and analyze the results of detailed FMR studies performed on films corresponding to per... more We report and analyze the results of detailed FMR studies performed on films corresponding to permalloy ultrathin layers sandwiched by Al2O3. It is shown that calculations based on a theoretical description of the inhomogeneous linewidth, including the effect of exchange narrowing, enable to reproduce rather well the magnitude and angular variation of the observed width.
Le Journal De Physique Colloques, 1988
FMR results, at E band and X band, were obtained for an iron layer (sandviriched by Ag and deposi... more FMR results, at E band and X band, were obtained for an iron layer (sandviriched by Ag and deposited on mica and bulk silver substrates), TESR measurements being also performed for the silver sample. Various effects induced by the coupling at the (Fe/Ag) interface are evidenced in the spectra and are to be dominantly associated to the diffusion of the conduction electron magnetization.
Journal of Magnetism and Magnetic Materials, 1991
The FMR spectrum, at X band and room temperature, is studied as a function of the dc field orient... more The FMR spectrum, at X band and room temperature, is studied as a function of the dc field orientation for a series of films constituted of (AgIFe bilayer]Ag) sandwiches where the Fe bilayers (FellAglFe2) have the same Fe layer thickness (36A) but a Ag spacer thickness varied in a large range. All the resonance characteristics of these Fe bilayers, when compared to the ones of a Fe single layer control sample, provide evidence for dynamic coupling effects between the two Fe layers which, we suggest, are to be associated with the diffusion of the conduction electron magnetization through the Ag spacer.
Journal of Magnetism and Magnetic Materials, 1982
Magnetic measurements reveal that the alloy Ni78Mn22 undergoes a field-induced spin-glass-to-ferr... more Magnetic measurements reveal that the alloy Ni78Mn22 undergoes a field-induced spin-glass-to-ferromagnetic transition at a critical field that decreases from ~ 140 Oe to zero as the temperature is raised from 4.2 to 40 K, its ferromagnetic Curie point being ~ 270 K. The alloy Ni74Mn26 is found to have a related state of infinite initial susceptibility but no spontaneous magnetization
Journal of Magnetism and Magnetic Materials, 1983
ESR spectra were obtained for disordered Ni74Mn26 cooled to ~ 4K in zero field and 10 kOe. The re... more ESR spectra were obtained for disordered Ni74Mn26 cooled to ~ 4K in zero field and 10 kOe. The resonance observed after field-cooling are asymmetric with the applied field direction up to ~ 30 K and continue to show a macroscopic anisotropy field up to ~ K, where a transition occurs from spin-glass to ferromagnetism.