Highlights
Theoretical and computational modeling of spintronic THz emitters

Key Advances

  • Ultrafast-light-driven magnetic heterostructures exhibit concurrent demagnetization and emission of THz radiation.

  • Despite being a primary experimental probe of spin-charge coupled dynamics and transport, there have been virtually no calculations of THz radiation from such systems since the inception of this field in 1996.

  • We solved this longstanding problem by introducing two new complementary frameworks, which combine time-dependent density functional theory (TDDFT) or time-dependent nonequilibrium Green’s functions (TDNEGF) with Jefimenko solutions of the Maxwell equations.

  • Our solutions make it possible to predict (and doubly confirm) a new effect (charge current pumping by ultrafast demagnetization), while concurrently explaining the microscopic origin of conjectured interlayer spin current.

Interdisciplinary Research Group (IRG 2):

Hybrid Quantum Materials with Emergent Terahertz Functionalities (HQ-METs)

For more information:

Phys. Rev. B 111, L140415 (2025), Phys. Rev. Lett. 133, 136704 (2024), Phys. Rev. B 110, L060410 (2024)

Fig. Illustration of ferromagnet/normal-metal (FM/NM) heterostructure whose FM layer is driven by femtosecond laser pulse (fsLP) and where our TDDFT+Jefimenko or TDNEGF+Jefimenko theoretical/computational approaches predict pumping of intralayer charge current Ix FM and interlayer spin current IzSα by demagnetization dynamics. Both eventually contribute to emitted THz radiation, which we compute for the first time from first principles theory.
Fig. Illustration of ferromagnet/normal-metal (FM/NM) heterostructure whose FM layer is driven by femtosecond laser pulse (fsLP) and where our TDDFT+Jefimenko or TDNEGF+Jefimenko theoretical/computational approaches predict pumping of intralayer charge current Ix FM and interlayer spin current IzSα by demagnetization dynamics. Both eventually contribute to emitted THz radiation, which we compute for the first time from first principles theory.
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Deciphering the origin of spin current in spintronic terahertz emitters and its imprint on their electromagnetic radiation via time-dependent density functional theory

Physical Review B
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