Tesla-Scale Terahertz Magnetic Impulses

Abstract

Measuring the magnetic response of matter relies acutely on the degree to which a magnetic field source's amplitude, spatial, and temporal character can be tailored. Magnetic fields are inseparable from light-matter interaction, yet due to the dominance of electric-field-induced effects in many systems, laser pulses have heretofore provided comparatively limited insight into the high-frequency magnetic response of matter. Conductors or superconductors arranged in a solenoidal configuration embody the state-ofthe-art apparatus for generating spatially isolated magnetic fields, but the reliance on electrical circuitry limits the field amplitude, pulse brevity, and absolute timing of the generated fields. We transfer the concept of solenoidal currents commonly leveraged in electromagnets to photo-ionized electrons driven by moderately intense vector laser beams, in a scheme that does not require the laser mode to carry orbital angular momentum. We predict that this all-optical approach will enable magnetic fields exceeding 8 Tesla to be turned on within 50 femtoseconds using moderate laser intensities, an unprecedented combination of parameters that will open the possibility for ultrafast metrological techniques to be combined with intense, spatially isolated, magnetic fields.Magnetic fields play a fundamental role in our understanding of magnetic materials [1], electron spins [2,3], superconductivity [4][5][6], quantum and topological systems [7-9], plasma and nuclear fusion [10-12], medical diagnosis [13], and astrophysics [14]. Electric charge in motion generates magnetic fields [15,16], and the arrangement of conductors or superconductors into loops or solenoids has been the workhorse approach to magnetic field sources for decades. Although effective for measuring the quasistatic magnetic response of matter, the ultrafast dynamics that ultimately produces this response remains largely inaccessible.As an alternative, relativistic electron bunches have been used to introduce a strong magnetic pulse of 2.3 ps duration to a granular recording film [17]. The application of large magnetic fields of short duration enables insight into the maximum switching bandwidth of the magnetic material before the onset of magnetic disorder. Although these results provide intriguing fundamental insight with important technological implications, the large-scale electron acceleration facility required for these measurements limits the exploration of ultrafast dynamics in other material systems.Extensive effort has been devoted to optically exciting solenoidal currents and high magnetic fields in underdense plasmas using relativistic laser pulses, for the purpose of charged beam collimation. Early approaches were based on the inverse Faraday effect [18], whereby the angular momentum is transferred from a circularly polarized beam to the plasma via dissipative effects. The recent availability of optical vortex beams [i.e., laser modes that carry orbital angular momentum (OAM)] at relativistic intensities [19] has motivated new approach...

Vectorized optoelectronic control and metrology in a semiconductor

“…3d, which is valid in the plane of the detector. This magnetic field will be the basis for all-optical generation of terahertz magnetic field impulses in future work 41 .…”

Magnetization switching in the inertial regime

“…Our results will be useful for the design of devices relying on ultrafast magnetization switching using picosecond magnetic field pulses. The realization of such short and intense magnetic fields have been suggested recently designing magnetic-field enhancing metamaterials 32 , by the use of vector laser beams 33 or thanks to ultrafast electronic switches 34 . Finally, we anticipate that our findings will be relevant to much of the recent works in the magnetism community aimed at the understanding of inertial spin dynamics [35][36][37][38][39][40][41][42][43][44][45][46][47][48] .…”

Electronic Currents and Magnetic Fields in H2+ Induced by Coherent Resonant Bichromatic Circularly Polarized Laser Pulses: Effects of Orientation, Phase, and Helicity

“…where p is the electron momentum tangent to the ring, one gets after performing the ∇ derivation a simple relation j D p m e Dv as shown in [58]. Next, for the case of the electron current mainly localized in a plane one gets from Eq.…”

“…Thus, in Eq. 6, the magnetic field is proportional to the electron probability density D and the electron velocity which originates from the electron current density j Dv [58]. Density D for the case of resonant transitions corresponds to the excited state transition probability, which is determined by the intrinsic transition dipole of molecules and the electric field strength as discussed in detail in Supplementary Appendix A2.…”