Themed collection From optical to THz control of materials

Controlling materials, especially quantum materials, is a key goal of physical science. Biology provides inspiration for control of materials and molecules via feedback loops.

Excitation in the valley domains of graphene, around K (warm colors) and K′ (cold colors) are induced by vertically-polarized multi-harmonic pulses (here containing ω and 2ω) with a maximum vector potential matching the distance K–K′.

We present time-resolved magneto-optical spectroscopy on the magnetic Mott–Hubbard-insulating Kitaev spin liquid candidate α-RuCl₃ to investigate the nonequilibrium dynamics of its antiferromagnetically ordered zigzag groundstate after photoexcitation.

The concept of using appropriately shaped pulses of light to control the properties of materials has a range of potential applications, and relies on an understanding of intricate couplings within the material.

Quantum coherences detected from ultrafast time-resolved absorption measurements are being explored to provide insight into the nature of the reaction coordinate for excited-state dynamics in transition metal complexes.

Optically-induced nanoscale strain dynamics in nano-fabricated Si thin films are quantitatively visualized on the picosecond scale. A newly developed ultrafast five-dimensional convergent beam electron diffraction method is introduced.

Herein, we investigate the coherent vibrational wavepacket dynamics during the intersystem crossing processes in a bimetallic Pt(II) complex.

The fifth harmonic generated current in the BCS superconductor with a double peak signature. The resonant contributions describe the coupling of collective excitations with 2 and 4 photons. The processes are shown diagrammatically as insets.

We calculate nonlinear magnetic dynamics induced by an intense THz pulse in an antiferromagnet. As a result, we reveal an inhomogeneous switching regime involving moving domain walls and propagating magnons.

The coherent control dynamics of interacting electron–phonon and qubit–spin systems is numerically studied. The time-evolution of the quantum many-body states is revealed from a viewpoint of quantum entanglement.

We show exemplarily for the ZnO surface that photoexcited deep defects act like chemically doped shallow donors in semiconductors. Sufficiently strong “photodoping” makes ZnO a transient metal with influenceable ultrashort to metastable lifetimes.

Ultrafast optical and X-ray spectroscopies reveal the multiscale out-of-equilibrium dynamics in photoexcited CsCoFe Prussian blue analogue nanocrystals; from local charge-transfer to macroscopic crystal breathing.

We calculate the nonlinear signal of a cuprate superconductor when subjected to a quenching and a driving field, showing transient features of the generated higher harmonics, as well as the enhancement of coherence in incoherent Cooper pairs.

Time-resolved spectroscopy of (TaSe₄)₂I, which embeds different electronic structures, sheds light on out-of-equilibrium states driven by optical or X-ray excitation.

The computation of 2D electronic spectroscopy signals of intra-chain excitons reveals vibronic fine structure due to high-frequency polaronic modes, along with a dynamic Stokes shift induced by soft torsional modes, indicative of exciton motion.

We present a theoretical study of thermal and light-induced high-to-low spin crossover in prototypical Fe(II) complexes. We have computed the transfer rate of the HS state thermal relaxation at several time scales in two different iron complexes.

We present a comprehensive investigation of ultrafast demagnetisation and accompanying band gap reduction in a charge transfer insulator using time-resolved resonant X-ray reflectivity.

Strain waves generated in pump probe experiments through thermoelastic interaction modulate transient optical transmission. Terahertz uniform or optical exponentially decaying pump profiles effects are investigated in metallic thin film V₂O₃.

We compute the nonlinear current J^NL induced by an intense THz field in superconducting cuprates. We find that J^NL is dominated by the BCS response, showing comparable para- and diamagnetic contributions, in agreement with θ-resolved THG experiments.

Unconventional stimulated emission and second harmonic generation (SHG) in an ultrafast no-scattering time window are induced by a nearly single-cycle 6 fs near infrared electric field of 10 MV cm⁻¹ in an organic superconductor (κ-(h-ET)₂Cu[N(CN)₂]Br).

Tracing the reflectivity modulation of a dielectric system in a strong field provides access to the electronic delay response of the system.