Transfer of angular momentum and effects of inertia of magnetization in spin dynamics The interaction of magnetic moments with various excitations is the foundation of spintronics – the energy-saving “electronics” based on spin manipulation, and its sub-field magnonics which is based on the coupling of microwave photons to quanta of magnetic excitations (spin waves). The control and transfer of spin angular momentum plays an important role in many future spintronic applications based for example on a spin-transfer torque and spin-to-charge interconversion. In magnetic bilayers, the transfer of angular momentum to an adjacent paramagnetic material can be controlled by the resonant precession of magnetization (typically at GHz frequencies) leading to a propagation of spin – not charge – current across the interface.
​ In my talk, I will discuss concepts of interface design for “spin pumping” based on epitaxial bilayers [1] and binary alloys with a magnetostructural transition [2,3] which can be switched from a paramagnetic to ferromagnetic state by inducing chemical disorder [4]. Being able to turn the material to a spin source or a spin sink offers an additional degree of freedom for new broadband functionalities in magnetophotonics, quantum optics and magnonic networks, based on laterally patterned tailored nanostructures.
​ As high speed information processing with THz frequencies has moved into the focus of research, I will discuss the challenges and opportunities of the recently revisited inertial regime of magnetization [5,6] in the second part of my talk. The key idea is inspired by a conceptually new realization of nutation, an additional motion of magnetization that occurs on picosecond timescales [7] and can be used to generate sub-THz and THz magnons by GHz excitation. The manipulation of spin on this timescale opens a complimentary pathway to new ultrafast and energy-efficient technology for data processing. As a result of inertia, nutation of the magnetization vector with 10 to 1000 times higher speed is superimposed on the regular GHz-frequency precession [7]. I will discuss the recent findings and possible consequences in anisotropic ferromagnets [8] and in nanomagnets, and show how this unconventional excitation scheme might advance THz magnonics and elegantly surpass current speed limitations in spintronic devices.
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More information :https://www.spintec.fr/seminar-transfer-of-angular-momentum-and-effects-of-inertia-of-magnetization-in-spin-dynamics/​

Videoconference ​: https://univ-grenoble-alpes-fr.zoom.us/j/98769867024