arXiv subjects

O. Ly

Publications and source records attributed to O. Ly.

4 recordsLinked to original sources

arXiv2023

Magnetic dynamics driven integer and fractional high harmonic generation arising from highly nonlinear instantaneous energy levels

We demonstrate that the strongly nonlinear regime of the magnetic dynamics driven high harmonic generation (HHG) can be captured through an adiabatic treatment. The underlying instantaneous energy dispersion reveal a highly nonlinear term that mirrors the high-frequency excitations present in non-equilibrium transport quantities. We stress out that the instantaneous energy levels dynamics carry much information on HHG and thereby provide a simplified understanding of the effect. Further, we exploit the present approach to predict the emergence of tunable integer and fractional high harmonics in the presence of a time-modulated spin-orbit interaction. Finally, we apply the approach to the case of the light driven HHG to figure out differently emerging non-linearities. Our findings initiate a new direction for harnessing HHG in both laser and precession driven ultrafast carrier dynamics.

cond-mat.mes-hall↗

arXiv2021

Spin-orbit coupling induced ultra-high harmonic generation from magnetic dynamics

The recent boost in data transfer rates puts a daring strain on information technology. Sustaining such a growth rate requires the development of sources, detectors and systems working in the so-called TeraHertz (THz) gap covering the frequency window from 0.1 to 10 THz (1 THz = 10$^{12}$~Hz). This gap represents a challenge for conventional electronic devices due to carrier transit delays ($\sim$1-10ps), as well as for photonic devices due to thermal fluctuations (300K$\sim$6THz). Nonetheless, designing efficient, room-temperature THz sources would constitute a key enabler to applications spanning from high-resolution imaging to extreme wide band wireless communication. Whereas high-harmonic generation in solid is usually limited to less than ten harmonics, broadband THz emission has been demonstrated using laser-induced superdiffusive spin currents in magnetic bilayers composed of a ferromagnet deposited on top of a noble metal. While promising, this technique presents the major disadvantage of necessitating optical pumping and hence lacks scalability. Here, we demonstrate that extremely high harmonic emission can be achieved by exploiting conventional spin pumping, without the need of optical excitation. We show that when the spin-orbit coupling strength is close to the s-d exchange energy, a strongly non linear regime resulting from resonant spin flip scattering occurs leading to the generation of a thousand of harmonics at realistic antiferromagnetic precession frequencies, thereby enhancing both spin and charge dynamics by two orders of magnitude, and allowing for an emission at frequencies above 300 THz.

cond-mat.mes-hall↗

arXiv2021

Topological Aspects of Antiferromagnets

The long fascination antiferromagnetic materials have exerted on the scientific community over about a century has been entirely renewed recently with the discovery of several unexpected phenomena including various classes of anomalous spin and charge Hall effects and unconventional magnonic transport, but also homochiral magnetic entities such as skyrmions. With these breakthroughs, antiferromagnets standout as a rich playground for the investigation of novel topological behaviors, and as promising candidate materials for disruptive low-power microelectronic applications. Remarkably, the newly discovered phenomena are all related to the topology of the magnetic, electronic or magnonic ground state of the antiferromagnets. This review exposes how non-trivial topology emerges at different levels in antiferromagnets and explores the novel mechanisms that have been discovered recently. We also discuss how novel classes of quantum magnets could enrich the currently expanding field of antiferromagnetic spintronics and how spin transport can in turn favor a better understanding of exotic quantum excitations.

cond-mat.mes-hall↗

arXiv2016

Theory of electron spin resonance in bulk topological insulators Bi2Se3, Bi2Te3 and Sb2Te3

We report a theoretical study of electron spin resonance in bulk topological insulators, such as Bi2Se3, Bi2Te3 and Sb2Te3. Using the effective four-band model, we find the electron energy spectrum in a static magnetic field and determine the response to electric and magnetic dipole perturbations, represented by oscillating electric and magnetic fields perpendicular to the static field. We determine the associated selection rules and calculate the absorption spectra. This enables us to separate the effective orbital and spin degrees of freedom and to determine the effective g-factors for electrons and holes.

cond-mat.mtrl-sci↗