Ultrafast demagnetization of ferromagnetic metals can be achieved by a heat pulse propagating in the electron gas of a non-magnetic metal layer, which absorbs a pump laser pulse. Demagnetization by electronic heating is investigated on samples with different thicknesses of the absorber layer on nickel. This allows us to separate the contribution of thermalized hot electrons compared to non-ther...

The laser-induced femtosecond demagnetization in ferromagnetic metals is investigated theoretically. Different from the conventional nanosecond one, this ultrafast demagnetization is a cooperative effect of the external laser field and the internal spin-orbit coupling. The spin-orbit coupling smears out the original identities of triplets and singlets while the laser field uses it as an avenue ...

The efficiency of the adiabatic demagnetization nuclear spin system (NSS) a solid is limited, if quadrupole effects are present. Nevertheless, despite considerable interaction, recent experiments validated thermodynamic description NSS in GaAs. This suggests that temperature can be used as probe magnetic resonances. We implement this idea by analyzing modification response to an oscillating fie...

Abstract Cooling the junction of a scanning tunneling microscope to millikelvin temperatures is fundamental for high-resolution spectroscopy. However, accurately determining temperature has proven elusive, due microscopic dimension and its continuous energy exchange with surrounding environment. Here, we employ tunnelling cooled by an adiabatic demagnetization refrigerator. Using normal-metal s...

Heat capacity of the nuclear spin system (NSS) in GaAs-based microstructures has been shown to be much greater than expected from dipolar coupling between nuclei, thus limiting efficiency NSS cooling by adiabatic demagnetization. It was suggested that quadrupole interaction induced some small residual strain could provide this additional reservoir for heat storage. We check and validate hypothe...

The laser-induced demagnetization of a ferromagnet is caused by the temperature of the electron gas as well as the lattice temperature. For long excitation pulses, the two reservoirs are in thermal equilibrium. In contrast to a picosecond laser pulse, a femtosecond pulse causes a non-equilibrium between the electron gas and the lattice. By pump pulse length dependent optical measurements, we fi...

To prevent irreversible demagnetization of a permanent magnet (PM) for interior permanent magnet synchronous motors (IPMSMs) by flux-weakening control, a robust PM flux-linkage nonsingular fast terminal-sliding-mode observer (NFTSMO) is proposed to detect demagnetization faults. First, the IPMSM mathematical model of demagnetization is presented. Second, the construction of the NFTSMO to estima...

We report ab initio simulations of the quantum dynamics of electronic charge and spins when subjected to intense laser pulses. By performing these purely electron-dynamics calculations for a thin film and for the bulk of Ni, we conclude that formation of surfaces has a dramatic influence of amplifying the laser induced demagnetization. The reason for this amplification is enhanced spin-currents...

The laser-induced ultrafast demagnetization of CoFeB/MgO/CoFeB magnetic tunneling junction is exploited by time-resolved magneto-optical Kerr effect (TRMOKE) for both the parallel state (P state) and the antiparallel state (AP state) of the magnetizations between two magnetic layers. It was observed that the demagnetization time is shorter and the magnitude of demagnetization is larger in the A...