Transient photoinduced ‘hidden’ phase in a manganite

Ichikawa, H.; Nozawa, Shiro; Sato, Tokushi; Tomita, Ayana; Ichiyanagi, Kouhei; Chollet, Matthieu; Guérin, Laurent; Dean, Nicky; Cavalleri, Andrea; Adachi, Shin‐ichi; Arima, T.; Sawa, Hiroshi; Ogimoto, Yasushi; Nakamura, Masao; Tamaki, Ryo; Miyano, Kenjiro; Koshihara, Shin‐ya

doi:10.1038/nmat2929

Cited by 259 publications

(206 citation statements)

References 29 publications

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“…T he ultrafast control of a material's properties via nonequilibrium states is a new method to manipulate and control the structural 1 , magnetic 2 and electrical 3 properties of materials that may not be accessible under equilibrium conditions. The timescale on which one phase is lost and a new phase emerges is of fundamental interest for understanding how these transitions occur as well as being important for potential applications.…”

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confidence: 99%

Ultrafast changes in lattice symmetry probed by coherent phonons

et al. 2012

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The electronic and structural properties of a material are strongly determined by its symmetry. Changing the symmetry via a photoinduced phase transition offers new ways to manipulate material properties on ultrafast timescales. However, to identify when and how fast these phase transitions occur, methods that can probe the symmetry change in the time domain are required. Here we show that a time-dependent change in the coherent phonon spectrum can probe a change in symmetry of the lattice potential, thus providing an all-optical probe of structural transitions. We examine the photoinduced structural phase transition in Vo 2 and show that, above the phase transition threshold, photoexcitation completely changes the lattice potential on an ultrafast timescale. The loss of the equilibrium-phase phonon modes occurs promptly, indicating a non-thermal pathway for the photoinduced phase transition, where a strong perturbation to the lattice potential changes its symmetry before ionic rearrangement has occurred.

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confidence: 99%

Ultrafast changes in lattice symmetry probed by coherent phonons

et al. 2012

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“…The electron pumping mechanism across a structural phase transition that we observe for Cu 2 S nanoplates will no doubt also be operating in other metastable and nonequilibrium phases as well, and for metal-insulator phase transitions in general in nanoparticles of complex materials (26)(27)(28).…”

Section: Significancementioning

confidence: 70%

Reversible structure manipulation by tuning carrier concentration in metastable Cu ₂ S

Tao

Chen

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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The optimal functionalities of materials often appear at phase transitions involving simultaneous changes in the electronic structure and the symmetry of the underlying lattice. It is experimentally challenging to disentangle which of the two effects--electronic or structural--is the driving force for the phase transition and to use the mechanism to control material properties. Here we report the concurrent pumping and probing of Cu 2 S nanoplates using an electron beam to directly manipulate the transition between two phases with distinctly different crystal symmetries and charge-carrier concentrations, and show that the transition is the result of charge generation for one phase and charge depletion for the other. We demonstrate that this manipulation is fully reversible and nonthermal in nature. Our observations reveal a phase-transition pathway in materials, where electron-induced changes in the electronic structure can lead to a macroscopic reconstruction of the crystal structure. functional and quantum materials--the key properties of functional materials are often born out of strong structural and electronic interactions that are quantum mechanical in nature. Notable examples include colossal magnetoresistance manganites (1), ferroelectrics (2), and valleytronic materials (3). The targeted functions are usually accompanied by symmetry breaking, induced through changes in temperature or under other external perturbations. A prominent question is whether the symmetry reduction has an origin in the lattice (e.g., in the form of displacement of atoms, and could be described reasonably well using first-principles calculations) or the electronic degrees of freedom (charge, spin, and orbital) (4-6). It is of great interest to distinguish the roles of these factors in phase transitions.Cu 2 S provides an intriguing example for addressing the above "chicken-and-egg" question (6), which is critical to the understanding of a wide range of functional and quantum materials. It is a fast ionic conductor (7) with highly mobile Cu ions. A phase transition in the bulk material occurs near 100°C from a semiconducting (8) monoclinic symmetry low-chalcocite phase (9) [hereafter called the "L-s phase" (i.e., low, semiconducting); space group P2 1 /c] to an electrically insulating (10) hexagonal symmetry high-chalcocite phase (7, 11) [hereafter called the "H-i phase" (i.e., high, insulating); space group P6 3 /mmc]. The coinciding changes in the bulk electrical conductivity and crystal structure present a possibility for exploring the relationship between electronic and structural phase transitions. Difficulties in the synthesis of stoichiometric Cu 2 S material and the lack of detailed theoretical treatments of both the crystal and the electronic structures of Cu 2 S have hindered the understanding of the phase transition (7, 11-13). Results and DiscussionWe have recently synthesized high-quality Cu 2 S nanoplates (Materials and Methods), which are on the order of 10-nm thick and 100 nm in lateral dimension ( Fig. 1 A and B)....

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“…6 On the other hand, photoirradiation may induce non-thermal metastable states or transient phases with optical, magnetic and electric properties distinct from that of the ground states. [7][8][9] Among these light-responsive materials, the ferromagnetic materials have been brought into sharp focus by laser-induced demagnetization since Bigot and coworkers found the ultrafast dropping of magnetization in nickel film following optical pulses in 1996. 6 Until recently, the ultrashort pulses of light are applied to manipulate the ultrafast processes in the antiferromagnets.…”

Section: Introductionmentioning

confidence: 99%

Model of ultrafast demagnetization driven by spin-orbit coupling in a photoexcited antiferromagnetic insulator Cr2O3

Guo

Zhang

Jin

et al. 2017

The Journal of Chemical Physics

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We theoretically study the dynamic time evolution following laser pulse pumping in an antiferromagnetic insulator Cr2O3. From the photoexcited high-spin quartet states to the long-lived low-spin doublet states, the ultrafast demagnetization processes are investigated by solving the dissipative Schrödinger equation. We find that the demagnetization times are of the order of hundreds of femtosecond, in good agreement with recent experiments. The switching times could be strongly reduced by properly tuning the energy gaps between the multiplet energy levels of Cr 3+ . Furthermore, the relaxation times also depend on the hybridization of atomic orbitals in the first photoexcited state. Our results suggest that the selective manipulation of electronic structure by engineering stress-strain or chemical substitution allows effective control of the magnetic state switching in photoexcited insulating transition-metal oxides.

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Transient photoinduced ‘hidden’ phase in a manganite

Cited by 259 publications

References 29 publications

Ultrafast changes in lattice symmetry probed by coherent phonons

Ultrafast changes in lattice symmetry probed by coherent phonons

Reversible structure manipulation by tuning carrier concentration in metastable Cu ₂ S

Model of ultrafast demagnetization driven by spin-orbit coupling in a photoexcited antiferromagnetic insulator Cr2O3

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Transient photoinduced ‘hidden’ phase in a manganite

Cited by 259 publications

References 29 publications

Ultrafast changes in lattice symmetry probed by coherent phonons

Ultrafast changes in lattice symmetry probed by coherent phonons

Reversible structure manipulation by tuning carrier concentration in metastable Cu 2 S

Model of ultrafast demagnetization driven by spin-orbit coupling in a photoexcited antiferromagnetic insulator Cr2O3

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Reversible structure manipulation by tuning carrier concentration in metastable Cu ₂ S