X-ray nanodiffraction imaging reveals distinct nanoscopic dynamics of an ultrafast phase transition

Ahn, Youngjun; Cherukara, Mathew J.; Cai, Zhonghou; Bartlein, Michael; Zhou, Tao; DiChiara, Anthony; Walko, Donald A.; Holt, Martin V.; Fullerton, Eric E.; Evans, Paul G.; Wen, Haidan

doi:10.1073/pnas.2118597119

Cited by 5 publications

(5 citation statements)

References 53 publications

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“…For thinner epitaxial FeRh films, the substrate-induced stress becomes more relevant and de-stressing is introduced by alternating AF and FM domains at shorter intervals. We suggest that this is the reason behind the observation of small size phase domains (≲500 nm) found so far in the literature for FeRh [30][31][32][33][34][35][36]. In our case, increasing the film thickness to 200 nm slightly reduces the relative weight of the elastic interaction coming from the substrate, allowing the formation of larger, micron-sized phase domains that can be visualized using optical microscopy.…”

Section: Nucleation and Growth Of Phase Domains In Zero Fieldsupporting

confidence: 71%

“…Furthermore, x-ray nanodiffraction experiments confirmed the sub-micron character of structural phase domains in FeRh [34,35]. FM domain evolution across the phase transition was also studied in real space with complementary techniques that are sensitive to magnetization, such as scanning electron microscopy with polarization analysis [36], electron holography and differential phase contrast in transmission electron microscopy [37,38], or nitrogen-vacancy-center magnetometry [39].…”

Section: Introductionmentioning

confidence: 92%

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Magnetic-field-controlled growth of magnetoelastic phase domains in FeRh

et al. 2023

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Magnetic phase transition materials are relevant building blocks for developing green technologies such as magnetocaloric devices for solid-state refrigeration. Their integration into applications requires a good understanding and controllability of their properties at the micro- and nanoscale. Here, we present an optical microscopy study of the phase domains in FeRh across its antiferromagnetic-ferromagnetic phase transition. By tracking the phase-dependent optical reflectivity, we establish that phase domains have typical sizes of a few microns for relatively thick epitaxial films (200 nm), thus enabling visualization of domain nucleation, growth, and percolation processes in great detail. Phase domain growth preferentially occurs along the principal crystallographic axes of FeRh, which is a consequence of the elastic adaptation to both the substrate-induced stress and laterally heterogeneous strain distributions arising from the different unit cell volumes of the two coexisting phases. Furthermore, we demonstrate a magnetic-field-controlled directional growth of phase domains during both heating and cooling, which is predominantly linked to the local effect of magnetic dipolar fields created by the alignment of magnetic moments in the emerging (disappearing) FM phase fraction during heating (cooling). These findings highlight the importance of the magnetoelastic character of phase domains for enabling the local control of micro- and nanoscale phase separation patterns using magnetic fields or elastic stresses.

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Section: Nucleation and Growth Of Phase Domains In Zero Fieldsupporting

confidence: 71%

Section: Introductionmentioning

confidence: 92%

Magnetic-field-controlled growth of magnetoelastic phase domains in FeRh

et al. 2023

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“…We performed optical pump/X‐ray diffraction nanoprobe microscopy ( Figure a) at Beamline 26‐ID‐C of the Advanced Photon Source (APS) (see Experimental Section). Our setup [ 26 ] employed a pulsed femtosecond laser (343 nm, 300 fs) as an optical excitation source with a repetition rate of 67 kHz. The optical excitation provided photons with above‐bandgap energy to directly create photocarriers in the BiFeO 3 sample.…”

Section: Resultsmentioning

confidence: 99%

“…[ 33 ] Such highly convergent X‐ray beam causes the diffraction to spread in q ‐space with an annulus ring shape on the detector (Figure 1c). [ 26 ] To visualize the ferroelectric domains, we performed diffraction imaging by raster scanning the nanoprobe X‐ray beam on the sample. We probed the (002) p Bragg peak of the rhombohedral BFO, where subscript P denotes the pseudo‐cubic unit cell.…”

Section: Resultsmentioning

confidence: 99%

Sub‐Nanosecond Reconfiguration of Ferroelectric Domains in Bismuth Ferrite

Guzelturk,

Yang,

Liu

et al. 2023

Advanced Materials

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Domain switching is crucial for achieving desired functions in ferroic materials that are used in various applications. Fast control of domains at subnanosecond timescales remains a challenge despite its potential for high‐speed operation in random‐access memories, photonic, and nanoelectronic devices. In this work, ultrafast laser excitation is shown to transiently melt and reconfigure ferroelectric stripe domains in multiferroic bismuth ferrite on a timescale faster than 100 ps. This dynamic behavior is visualized by picosecond‐ and nanometer‐resolved X‐ray diffraction measurements as well as time‐resolved X‐ray diffuse scattering. The disordering of stripe domains is attributed to the screening of depolarization fields by photogenerated carriers resulting in the formation of charged domain walls, as supported by phase field simulations. Furthermore, the recovery of disordered domains exhibits subdiffusive growth on nanosecond timescales, with a nonequilibrium domain velocity reaching up to 10 m/s. These findings present a new approach to image and manipulate ferroelectric domains on subnanosecond timescales, which can be further extended into other photoferroic systems to modulate their electronic, optical, and magnetic properties beyond GHz frequencies. This approach could pave the way for high‐speed ferroelectric data storage, computing and photonic applications in a range of photoferroics, and, more broadly, defines new approaches for visualizing the non‐equilibrium dynamics of heterogeneous and disordered materials.This article is protected by copyright. All rights reserved

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“…The latent heat and lattice expansion at the first-order AFM-FM phase transition were taken into account in the thermal transport simulation. The heat transport in the plane of the sample, as previously observed using nanodiffraction, 27 was neglected because the length scale of the in-plane thermal transport (∼100 nm) is much smaller than the probing X-ray beam size (50 μm).…”

Section: Resultsmentioning

confidence: 99%

Ultrafast Switching of Interfacial Thermal Conductance

Ahn,

Zhang,

Chu

et al. 2023

ACS Nano

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Dynamical control of thermal transport at the nanoscale provides a time-domain strategy for optimizing thermal management in nanoelectronics, magnetic devices, and thermoelectric devices. However, the rate of change available for thermal switches and regulators is limited to millisecond time scales, calling for a faster modulation speed. Here, time-resolved X-ray diffraction measurements and thermal transport modeling reveal an ultrafast modulation of the interfacial thermal conductance of an FeRh/MgO heterostructure as a result of a structural phase transition driven by optical excitation. Within 90 ps after optical excitation, the interfacial thermal conductance is reduced by a factor of 5 and lasts for a few nanoseconds, in comparison to the value at the equilibrium FeRh/MgO interface. The experimental results combined with thermal transport calculations suggest that the reduced interfacial thermal conductance results from enhanced phonon scattering at the interface where the lattice experiences transient in-plane biaxial stress due to the structural phase transition of FeRh. Our results suggest that optically driven phase transitions can be utilized for ultrafast nanoscale thermal switches for device application.

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X-ray nanodiffraction imaging reveals distinct nanoscopic dynamics of an ultrafast phase transition

Cited by 5 publications

References 53 publications

Magnetic-field-controlled growth of magnetoelastic phase domains in FeRh

Magnetic-field-controlled growth of magnetoelastic phase domains in FeRh

Sub‐Nanosecond Reconfiguration of Ferroelectric Domains in Bismuth Ferrite

Ultrafast Switching of Interfacial Thermal Conductance

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