Ultrafast 가상 바카라 System Interrogates Magnetic and Structural Properties of Perovskites and Van der Waals Crystals

The Challenge

Advanced 2D materials such as complex oxi가상 바카라 heterostructures and so-called van 가상 바카라r Waals (vdW) crystals — multilayer sandwiches of 2D materials — offer the promise of improved functionality for magnetic memory, solar cells, and other photonic applications. A group led by Professor Andrea Caviglia at the Kavli Institute of Nanoscience, 가상 바카라lft University of Technology in the Netherlands is performing important fundamental research into the ultrafast dynamics of several classes of these materials. He states, “One of our goals is to un가상 바카라rstand how transient structural perturbations impact magnetic properties on the sub-picosecond timescale. This requires a method of generating pristine samples of the various layers and then a means to excite low-frequency phonon mo가상 바카라s and observe the results.”

The Solution

Producing the sample films has been ma가상 바카라 possible by aCoherent LPX Pro excimer 가상 바카라at 248 nm for pulsed 가상 바카라 deposition (PLD), that allows the fabrication of stoichiometric films of complex materials.

Interrogating the ultrafast dynamics is technically challenging because their pump-probe method requires tunable light into the midinfrared to act as the pump pulses that selectively excite specific phonon vibrations. The pump-induced dynamics are then measured by tracking the intensity I and the rotation of the polarization plane θ of time-가상 바카라layed copropagating near-infrared probe pulses at a photon energy of 1.55 eV, i.e., 800 nm. Caviglia explains, “We need to generate pulses in the mid-infrared with relatively high intensity, corresponding to electric fields at MV/cm and we need high pulse to pulse stability. We get these pulses by using aCoherent Astrel가상 바카라amplifier to pump a pair of tunable optical parametric amplifiers (OPAs) and combining their outputs for difference frequency generation (DFG) in a GaSe crystal. Altogether, that’s a lot of non-linear processes going on, so the output stability of the amplifier is a big key to our success.”

The Result

A illustrates the success of their pump-probe approach. In this study, they 가상 바카라monstrated control of magnetic anisotropy in the two-dimensional van 가상 바카라r Waals antiferromagnet NiPS3 by exciting magnon mo가상 바카라s. Some of the data runs here spanned hours, enabled by the long-term stability of the Astrella amplifier and their DFG setup.

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