Abstract
Light–wave quantum electronics utilizes the oscillating carrier wave to control electronic properties with intense laser pulses. Without direct light–spin interactions, however, magnetic properties can only be indirectly affected by the light electric field, mostly at later times. A grand challenge is how to establish a universal principle for quantum control of charge and spin fluctuations, which can allow for faster-than-THz clock rates. Using quantum kinetic equations for the density matrix describing non–equilibrium states of Hubbard quasiparticles, here we show that time–periodic modulation of electronic hopping during few cycles of carrier–wave oscillations can dynamically steer an antiferromagnetic insulating state into a metalic state with transient magnetization. While nonlinearities associated with quasi-stationary Floquet states have been achieved before, magneto–electronics based on quasiparticle acceleration by time–periodic multi–cycle fields and quantum femtosecond/attosecond magnetism via strongly–coupled charge–spin quantum excitations represents an alternative way of controlling magnetic moments in sync with quantum transport.
Discussion
We have shown that light-driven itinerant electron spin and charge quantum excitations that interact strongly with an AFM local spin background can destabilize an equilibrium AFM insulating state with lattice displacements Qi ≠ 0 towards a metallic transient state with Qi ~ 0 and finite magnetization. Based on these results, we can envision in sync quantum THz tuning and coherent control of electronic and magnetic properties of quantum materials by tunable multicycle THz/MIR electric fields. For example, recent results in topological quantum materials indicate that a metastable phase with unique topological switching dynamics assisted by phonons emerges during cycles of lattice coherence oscillations, driven by a few-cycle THz electric field above threshold6,35. Also, coherent control of structural phase transitions9 has been suggested. Importantly, the ability to experimentally control coherent electronic transport on sub-cycle timescales sets the stage for attosecond magnetism2, quantum femtosecond magnetism5,52,55,57,77,78,79,80, and light-wave quantum electronics1,3,4,25,41,42 before the system reaches a steady state. Our results suggest a microscopic mechanism of quantum femtosecond/attosecond magnetism2,5,77,78 driven by the light electric field and spin quantum fluctuations. In weakly correlated magnetic systems, it has been debated whether femtosecond magnetization arises from adiabatic processes associated with electron, spin, and phonon populations, or from coherent processes associated with angular momenta interacting with photoexcited electrons55,77. Here, we propose a different mechanism, based on the strong coupling of electric quantum transport with local moment quantum fluctuations. Understanding the time evolution of a quantum state by simultaneous light-wave control of electronic, magnetic, and lattice properties prior to heating is important for THz magneto-electronics and coherent spintronics, as well for designing quantum materials properties far from equilibrium, leading, for example, to a light-induced switch that twists both spins and the crystal lattice35.
Author information
Affiliations
Department of Physics, University of Crete, Box 2208, Heraklion, Crete, 71003, Greece
Panagiotis C. Lingos
Department of Physics, University of Alabama at Birmingham, Birmingham, AL, 35294-1170, USA
Myron D. Kapetanakis & Ilias E. Perakis
Department of Physics and Astronomy, Iowa State University and Ames Laboratory—USDOE, Ames, IA, 50011, USA
Jigang Wang
Contributions
P.C.L., M.D.K., and I.E.P. developed the theory, performed the numerical calculations, and analyzed the numerical data. J.W. contributed to the analysis and interpretation of the numerical data. I.E.P. conceived, designed, and supervised the study, and wrote the paper with help from all authors.
Corresponding author
Correspondence to Ilias E. Perakis.
Edited for brevity by Alan Smith.
