A5073831282- Magnetic and transport properties of perovskites and related materials
- Multiferroics and related materials
- Advanced Condensed Matter Physics
- Electronic and Structural Properties of Oxides
- Organic and Molecular Conductors Research
- Advanced Chemical Physics Studies
- Ferroelectric and Piezoelectric Materials
- Photorefractive and Nonlinear Optics
- Magnetic properties of thin films
- High-pressure geophysics and materials
- Topological Materials and Phenomena
- Iron-based superconductors research
- Advanced Electron Microscopy Techniques and Applications
- Physics of Superconductivity and Magnetism
- Atomic and Subatomic Physics Research
- Magneto-Optical Properties and Applications
- Acoustic Wave Resonator Technologies
- Quantum and electron transport phenomena
- Underwater Acoustics Research
- Spectroscopy and Quantum Chemical Studies
- Terahertz technology and applications
- Quantum, superfluid, helium dynamics
- Gyrotron and Vacuum Electronics Research
ETH Zurich
2013-2019
Multiferroics have attracted strong interest for potential applications where electric fields control magnetic order. The ultimate speed of via magnetoelectric coupling, however, remains largely unexplored. Here, we report an experiment in which drove spin dynamics multiferroic TbMnO3 with intense few-cycle terahertz (THz) light pulse tuned to resonance electromagnon, electric-dipole active excitation. We observed the resulting motion using time-resolved resonant soft x-ray diffraction. Our...
Visualizing ferroelectric domains Multiferroic materials support intertwined ferromagnetic and orders, with the magnetic field capable of controlling electric order vice versa. Matsubara et al. used second harmonic generation microscopy to visualize what happens in multiferroic TbMnO 3 when an externally applied changes direction polarization by 90°. Unexpectedly, domain walls, initially parallel vector, did not change their shape or position. The resulting transition from neutral charged...
Using femtosecond time-resolved x-ray diffraction, we directly monitor the coherent lattice dynamics through an ultrafast charge-density-wave-to-metal transition in prototypical Peierls system ${\mathrm{K}}_{0.3}{\mathrm{MoO}}_{3}$ over a wide range of relevant excitation fluences. While low fluence regime follow structural associated with collective amplitude mode; for fluences above melting threshold electronic density modulation observe transient recovery periodic distortion. We can...
We performed ultrafast time-resolved near-infrared pump, resonant soft x-ray diffraction probe measurements to investigate the coupling between photoexcited electronic system and spin cycloid magnetic order in multiferroic $\mathrm{TbMn}{\mathrm{O}}_{3}$ at low temperatures. observe melting of long range antiferromagnetic excitation fluences with a decay time constant $22.3\ifmmode\pm\else\textpm\fi{}1.1\phantom{\rule{0.16em}{0ex}}\mathrm{ps}$, which is much slower than \ensuremath{\sim}1 ps...
The ultrafast dynamics of the octahedral rotation in $\mathrm{Ca}:\mathrm{SrTi}{\mathrm{O}}_{3}$ is studied by time-resolved x-ray diffraction after photoexcitation over band gap. By monitoring intensity a superlattice reflection that directly related to structural order parameter soft-mode driven antiferrodistortive phase $\mathrm{Ca}:\mathrm{SrTi}{\mathrm{O}}_{3}$, we observe an relaxation on 0.2 ps timescale oxygen octahedron, which found be independent initial temperature despite large...
The strength of the electron-phonon coupling parameter and its evolution throughout a solid's phase diagram often determines phenomena such as superconductivity, charge- spin-density waves. Its experimental determination relies on ability to distinguish thermally activated phonons from those emitted by conduction band electrons, which can be achieved in an elegant way ultrafast techniques. Separating electronic out-of-equilibrium lattice subsystems, we probed their re-equilibration...
Femtosecond time-resolved x-ray diffraction is employed to study the dynamics of periodic lattice distortion (PLD) associated with charge-density-wave (CDW) in K0.3MoO3. Using a multi-pulse scheme we show ability extend lifetime coherent oscillations PLD about undistorted structure through re-excitation electronic states. This suggests that it possible enter regime where symmetry potential energy landscape corresponds high phase but scattering pathways lead damping are still controllable by...
We investigate the structural and magnetic origins of unusual ultrafast second-harmonicgeneration (SHG) response femtosecond-laser-excited nickel oxide (NiO) previously attributed to oscillatory reorientation dynamics structure induced by d-d excitations. Using time-resolved x-ray diffraction from (3/2 3/2 3/2) planes, we show that changes in magnitude factor following optical excitation are limited $\Delta<F_m>/<F_m>$ = 1.5% first 30 ps. An extended investigation SHG reveals a strong...
Recent ultrafast magnetic-sensitive measurements [Phys. Rev. B 92, 184429 (2015) and Phys. 96, 184414 (2017)] have revealed a delayed melting of the long-range cycloid spin-order in TbMnO$_3$ following photoexcitation across fundamental Mott-Hubbard gap. The microscopic mechanism behind this slow transfer energy from photoexcited carriers to spin degrees freedom is still elusive not understood. Here, we address problem by combining spectroscopic ellipsometry, broadband optical spectroscopy...
Intense, few-cycle pulses in the terahertz frequency range have strong potential for schemes of control over vibrational modes solid-state materials electronic ground-state. Here we report an experiment using single cycle to directly excite lattice vibrations ferroelectric material $\mathrm{Sn_2P_2S_6}$ and ultrafast x-ray diffraction quantify resulting structural dynamics. A model a damped harmonic oscillator driven by transient electric field describes well movement Sn$^{2+}$ ion along...
We report on the ultrafast dynamics of charge order and structural response during photoinduced suppression orbital in a mixed-valence manganite. Employing femtosecond time-resolved resonant x-ray diffraction below at Mn $K$ absorption edge, we present method to disentangle transient thin films ${\mathrm{Pr}}_{0.5}{\mathrm{Ca}}_{0.5}{\mathrm{MnO}}_{3}$. Based static scattering spectra, extract dispersion correction charge-ordered ${\mathrm{Mn}}^{3+}$ ${\mathrm{Mn}}^{4+}$ ions, allowing us...
We investigate the demagnetization dynamics of cycloidal and sinusoidal phases multiferroic ${\mathrm{TbMnO}}_{3}$ by means time-resolved resonant soft x-ray diffraction following excitation an optical pump. The use orthogonal linear polarizations provides information on contribution from different magnetic moment directions, which can be interpreted as signatures spin order order. Tracking these in time domain enables us to identify transient phase created intense photoexcitation electrons...
We apply time-resolved resonant x-ray diffraction near the Mn K-edge to directly measure structural and electronic long-range order changes during ultrafast melting of charge orbitally ordered phase in a perovskite manganite.
We use time-resolved hard x-ray diffraction to directly follow the dynamics of structural symmetry change during ultrafast melting a charge density wave. observe transient recovery periodic lattice distortion on sub-picosecond timescale.
We photoexcite SrTiO 3 and EuTiO in their purely soft-mode-driven structurally distorted phase trace the structural order parameter via ultra-short x-rays. observe a rapid decay for an intriguing transient enhancement EuTiO3.