Ultrafast manipulation of magnetic anisotropy in a uniaxial intermetallic heterostructure TbCo2/FeCo

2022 ◽  
Author(s):  
Sergei Ovcharenko ◽  
Mikhail Gaponov ◽  
Aleksey A Klimov ◽  
Nicolas Tiercelin ◽  
Philippe Pernod ◽  
...  
Keyword(s):  
Magnetic Anisotropy ◽  
Anisotropy Field ◽  
Initial State ◽  
Kerr Rotation ◽  
Optical Pump ◽  
Pump Probe ◽  
High Frequency Oscillations ◽  
Order Of Magnitude ◽  
Stage Process ◽  
Strongly Damped

Abstract We study experimentally and theoretically the dynamics of spin relaxation motion excited by a femtosecond pulse in the TbCo2/FeCo multilayer structures with different ratios of TbCo2 to FeCo thicknesses rd = dTbCo2 / dFeCo. The main attribute of the structure is in-plane magnetic anisotropy artificially induced during sputtering under DC magnetic field. The optical pump-probe method revealed strongly damped high-frequency oscillations of the dynamical Kerr rotation angle, followed by its slow relaxation to the initial state. Modeling experimental results using the Landau-Lifshitz-Gilbert (LLG) equation showed that the observed entire dynamics is due to destruction and restoration of magnetic anisotropy rather than to demagnetization. For the pumping fluence of 7 mJ/cm2, the maximal photo-induced disruption of the anisotropy field is about 14% for the sample with rd = 1 and decreases when rd increases. The anisotropy relaxation is a three-stage process: the ultrafast one occurs within several picoseconds, and the slow one occurs on a nanosecond time scale. The Gilbert damping in the multilayers is found one order of magnitude higher than that in the constituent monolayers.

Pump-Probe Measurements Using Silicon Nanocrystal Waveguides

2003 ◽  
Vol 770 ◽  
Author(s):  
Nathanael Smith ◽  
Max J. Lederer ◽  
Marek Samoc ◽  
Barry Luther-Davies ◽  
Robert G. Elliman
Keyword(s):  
Probe Beam ◽  
Time Resolution ◽  
Pump Beam ◽  
Silicon Nanocrystals ◽  
Continuous Wave ◽  
Optical Gain ◽  
Optical Pump ◽  
Time Resolved ◽  
Pump Probe ◽  
Probe Measurements

AbstractOptical pump-probe measurements were performed on planar slab waveguides containing silicon nanocrystals in an attempt to measure optical gain from photo-excited silicon nanocrystals. Two experiments were performed, one with a continuous-wave probe beam and a pulsed pump beam, giving a time resolution of approximately 25 ns, and the other with a pulsed pump and probe beam, giving a time resolution of approximately 10 ps. In both cases the intensity of the probe beam was found to be attenuated by the pump beam, with the attenuation increasing monotonically with increasing pump power. Time-resolved measurements using the first experimental arrangement showed that the probe signal recovered its initial intensity on a time scale of 45-70 μs, a value comparable to the exciton lifetime in Si nanocrystals. These data are shown to be consistent with an induced absorption process such as confined carrier absorption. No evidence for optical gain was observed.

Losses in ac of BSCCO-2223 superconducting monofilament and multifilament tapes at power frequencies

1997 ◽  
Vol 12 (11) ◽  
pp. 3085-3089
Author(s):  
S. Mench ◽  
M. Lelovic ◽  
T. Deis ◽  
N. G. Eror ◽  
U. Balachandran ◽  
...  
Keyword(s):  
Eddy Current ◽  
Anisotropy Field ◽  
Magnetic Losses ◽  
Field Orientation ◽  
Eddy Current Losses ◽  
Order Of Magnitude

The ac magnetic losses at power frequencies (60 Hz) were investigated for mono- and multifilament Ag-sheathed (Bi, Pb)2Sr2Ca2Cu3Oy (BSCCO-2223) tapes with similar Ic values at 77 K. The multifilament sample exhibited higher losses than the monofilament under the same conditions. Loss peaks are discussed in terms of intergranular, intragranular, and eddy current losses. Because of BSCCO's anisotropy, field orientation has a large effect on the magnitude of these peaks, even at relatively small angles. Losses for fields applied parallel to the c-axis of the textured BSCCO grains are larger by over an order of magnitude than those applied perpendicular.

Effect of Thickness on Mechanically Tunable Magnetic Anisotropy of FeGa Thin Films Deposited on Flexible Substrates

2015 ◽  
Vol 815 ◽  
pp. 227-232 ◽  
Author(s):  
Ying Yu ◽  
Shu Hong Xie ◽  
Qing Feng Zhan
Keyword(s):  
Thin Films ◽  
Magnetic Properties ◽  
Magnetic Anisotropy ◽  
Effective Strain ◽  
Anisotropy Field ◽  
Saturation Field ◽  
Effective Anisotropy ◽  
Magnetostriction Constant ◽  
The Difference ◽  
Different Strains

A practical way to manipulate the magnetic anisotropy of magnetostrictive FeGa thin films grown on flexible polyethylene terephthalate (PET) substrates is introduced in this study. The effect of film thickness on magnetic properties and magnetostriction constant of polycrystalline FeGa thin films was investigated. The anisotropy field Hk of flexible FeGa films, i.e., the saturation field determined by fitting the hysteresis curves measured along the hard axis, was enhanced with increasing the tensile strain applied along the easy axis of the thin films, but this enhancement via strain became unconspicuous with increasing the thickness of FeGa films. In order to study the magnetic sensitivity of thin films responding to the external stress, we applied different strains on these films and measure the corresponding anisotropy field. Moreover, the effective magnetostriction constant of FeGa films was calculated from the changes of both anisotropy field and external strain based on the Villari effect. A Neel’s phenomenological model was developed to illustrate that the effective anisotropy field of FeGa thin films was contributed from both the constant volume term and the inverse thickness dependent surface term. Therefore, the magnetic properties for the volume and surface of FeGa thin films were different, which has been verified in this work by using vibrating sample magnetometer (VSM) and magneto-optic Kerr effect (MOKE) system. The anisotropy field contributed by the surface of FeGa film and obtained by MOKE is smaller than that contributed by the film volume and measured by VSM. We ascribed the difference in Hk to the relaxation of the effective strain applied on the films with increasing the thickness of films.

Gilbert Damping for Various Ni80Fe20Thin Films Investigated Using All-Optical Pump–Probe Detection and Ferromagnetic Resonance

2008 ◽  
Vol 1 ◽  
pp. 121301 ◽  
Author(s):  
Shigemi Mizukami ◽  
Hiroyuki Abe ◽  
Daisuke Watanabe ◽  
Mikihiko Oogane ◽  
Yasuo Ando ◽  
...  
Keyword(s):  
Ferromagnetic Resonance ◽  
Optical Pump ◽  
Gilbert Damping ◽  
Pump Probe ◽  
Probe Detection ◽  
All Optical

scholarly journals Measurement of effective magnetic anisotropy field and ferromagnetic resonance bandwidth at ferromagnetic resonance frequency in magnetically uniaxial hexagonal ferrites

2019 ◽  
Vol 5 (1) ◽  
pp. 33-39
Author(s):  
Alexey S. Semenov ◽  
Aleksey G. Nalogin ◽  
Sergey V. Shcherbakov ◽  
Alexander V. Myasnikov ◽  
Igor M. Isaev ◽  
...  
Keyword(s):  
Magnetic Anisotropy ◽  
Ferromagnetic Resonance ◽  
Transmission Lines ◽  
Anisotropy Field ◽  
Nominal Composition ◽  
Hexagonal Ferrites ◽  
Magnetic Texture ◽  
Measurement Results ◽  
Effective Magnetic Anisotropy ◽  
Ferromagnetic Resonance Frequency

In this work we have considered metrological problems and measurement of magnetic parameters and presented methods of measuring effective magnetic anisotropy field HAeff and ferromagnetic resonance bandwidth ∆H in magnetically uniaxial hexagonal ferrites in the electromagnetic microwave working frequency range. The methods allow measuring HAeff in the 10–23 and 28–40 kE ranges and ∆H in the 0.5–5.0 range. One method (suitable for wavelength measurements in free space in the 3-mm wavelength range) has been implemented for the 78.33–118.1 GHz range. The other method (based on the use of microstrip transmission lines) has been implemented for the 25–67 GHz range. The methods have been tested for polycrystalline specimens of hexagonal barium and strontium ferrites with nominal composition or complex substituted and having high magnetic texture. The measurement results have been compared with those obtained using conventional measurement methods and spherical specimens. Our methods prove to be highly accurate and reliable.

scholarly journals Обнаружение высокочастотных альфвеновских колебаний в омических разрядах сферического токамака Глобус-М2

2021 ◽  
Vol 47 (12) ◽  
pp. 17
Author(s):  
И.М. Балаченков ◽  
Ю.В. Петров ◽  
В.К. Гусев ◽  
Н.Н. Бахарев ◽  
В.И. Варфоломеев ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Standing Wave ◽  
High Frequency ◽  
Low Density ◽  
Frequency Range ◽  
High Frequency Oscillations ◽  
Model Predictions ◽  
Mode Excitation ◽  
Order Of Magnitude ◽  
Frequency Chirping

In Globus-M2 ohmic discharges with low density, by means of Mirnov coils array, magnetic field oscillations with frequencies in 1 MHz range were detected. Frequency range of these oscillations significantly exceed the range of TAE and RSAE frequencies, which were previously observed on Globus-M and Globus-M2 tokamaks, and their amplitude, contrary, turned out to be up to an order of magnitude lower. It was found that high frequency oscillations are interrelated with suprathermal electron fraction. At the same time the observed instability seems to have Alfvenic nature, since its frequency correlates well with Alfven frequency scaling. It was also found that magnetic perturbation always forms standing wave with predominantly low toroidal wavenumbers, including n = 0 structure, which makes gap (e.g. TAE) mode excitation impossible. Frequency chirping during single bursts with δω ~ √t is consistent with hole-clump model predictions.

scholarly journals Эпитаксиальные напряжения в фотопроводящем слое InGaAs для THz-антенн

2017 ◽  
Vol 43 (22) ◽  
pp. 48
Author(s):  
Д.И Хусяинов ◽  
А.М. Буряков ◽  
В.Р. Билык ◽  
Е.Д. Мишина ◽  
Д.С. Пономарев ◽  
...  
Keyword(s):  
Optical Pump ◽  
Pump Probe

Методами оптического зондирования при фемтосекундной лазерной накачке (optical pump-probe) и терагерцевой спектроскопии во временной области исследовано влияние эпитаксиальных напряжений на динамику неравновесных носителей заряда, а также спектр терагерцевого излучения в пленках InyGa1-yAs. Продемонстрировано снижение времени жизни неравновесных носителей заряда и увеличение ширины спектра терагерцевого излучения для пленки InyGa1-yAs с большим механическим напряжением. DOI: 10.21883/PJTF.2017.22.45260.16958

Thermal Transport From Gold Nanorod to Solvent, an Investigation of Ligand Effects by Ultrafast Laser Spectroscopy

2008 ◽  
Author(s):  
Joshua Alper ◽  
Aaron Schmidt ◽  
Kimberly Hamad-Schifferli
Keyword(s):  
Heat Transfer ◽  
Thermal Properties ◽  
Gold Nanorods ◽  
Thermal Transport ◽  
Ultrafast Laser ◽  
Ultrafast Laser Spectroscopy ◽  
Optical Pump ◽  
Thermal Interface ◽  
Pump Probe ◽  
Ligand Effects

To facilitate analysis of nanoscale heat transfer in nanoparticle systems the thermal properties of ligand layers must be understood. To this end, we use an optical pump-probe technique to study the thermal transport across ligands on gold nanorods and into the solvent. We find that varying properties of the ligand can have large impacts on the thermal decay of a nanorod after exposure to a laser pulse. By raising the concentration of free CTAB from 1 mM and 10 mM in solutions, the CTAB layer’s effective thermal interface conductance increases three fold. The transition occurs near the CTAB critical micelle concentration. Similar results are found for other ligand layers.

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