Aperiodic Spin State Ordering of Bistable Molecules and Its Photoinduced Erasing

Collet, Éric; Watanabe, Hiroshi; Bréfuel, Nicolas; Palatinus, Lukáš; Roudaut, Ludovic; Toupet, Loı̈c; Tanaka, Kōichiro; Tuchagues, Jean‐Pierre; Fertey, Pierre; Ravy, S.; Toudic, Bertrand; Cailleau, H.

doi:10.1103/physrevlett.109.257206

Cited by 57 publications

(69 citation statements)

References 29 publications

(46 reference statements)

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“…However, even if there is a unique SCO center in the crystal, inequivalence between SCO centers may spontaneously originate as a consequence of crystallographic symmetry breaking. Although, crystallographic symmetry breaking giving intermediate steps was previously observed for the mononuclear SCO complexes [Fe 27-29 So far, a relatively small number of complete two-step or incomplete (only one step of two expected) SCO events with symmetry breaking have been observed in mononuclear, [30][31][32][33][34][35][36][37][38][39] polynuclear, [40][41][42][43] and polymeric [44][45][46][47][48][49][50][51][52][53] Fe II SCO complexes, and reviewed recently. 54,55 This phenomenology has also been described for a reduced number of Fe III , [56][57][58][59][60] Co II 61 and Mn III 62 complexes.…”

Section: Introductionmentioning

confidence: 99%

Competing Phases Involving Spin-State and Ligand Structural Orderings in a Multistable Two-Dimensional Spin Crossover Coordination Polymer

Trzop

Valverde‐Muñoz

Piñeiro‐López

et al. 2017

Crystal Growth & Design

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Competition between spin-crossover (SCO) and structural ligand ordering is identified as responsible for multi-stability and generation of six different phases in a rigid two-dimensional (2D) coordination polymer formulated {Fe Furthermore, two additional phases are generated at low temperature. One, LS2 (HS = 0, phase 5), is due to spontaneous symmetry breaking of the LS1 state below 85 K. The other, results from irradiating the low-temperature LS2 phase at 15 K with red light to photo-generate a HS phase of low symmetry (HS*) (HS = 1, phase 6). Detailed structural studies of the six phases unravel the pivotal role played by the internal dihedral angle of the 4,4'-bipy ligands in the microscopic mechanism responsible for multistability and multi-step behavior in 1.Competing phases involving spin-state and ligand structural orderings in a multistable two-dimensional spin crossover coordination polymer INTRODUCTIONIron(II) spin crossover (SCO) complexes are switchable molecular materials that respond to environmental stimuli (T, P, light, analytes) through changes in magnetic, optical, electrical and mechanical properties associated with the high-(HS) and low-spin (LS) states of the SCO centre. The intrinsic on-off nature of the LSHS switch has attracted much interest not only because it constitutes an excellent platform for investigating models of thermal-, pressure and photoinduced phase transitions 1-13 in molecular materials but also because many expectancies have been created regarding to the conception of SCO-based devices, i.e. sensors, actuators and memories. [14][15][16][17][18][19][20][21][22][23][24] This has led to an impressive growth of the SCO field in the last decade as a result of cross-seeding interaction between different areas of research ranging from coordination chemistry, materials science and solid state physics.A pivotal current aspect that transcends the SCO research is the understanding of the elusive principles underlying cooperativity in multi-step spin transitions in the solid-state.Steps may occur when elastic forces favor competition between spatial periodicities of structural inequivalent SCO centers. For example, the presence of crystallographically distinct sites with different ligand field strengths. However, even if there is a unique SCO center in the crystal, inequivalence between SCO centers may spontaneously originate as a consequence of crystallographic symmetry breaking. Although, crystallographic symmetry breaking giving intermediate steps was previously observed for the mononuclear SCO complexes [Fe

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Section: Introductionmentioning

confidence: 99%

Competing Phases Involving Spin-State and Ligand Structural Orderings in a Multistable Two-Dimensional Spin Crossover Coordination Polymer

Trzop

Valverde‐Muñoz

Piñeiro‐López

et al. 2017

Crystal Growth & Design

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“…[1][2][3][4][5][6] In this context, metals are often used as a playground to study the dynamics of an excited electron gas. The fast and complex nuclear dynamics following electronic excitation can now be probed more directly by ultrafast electron diffraction (UED) and time-resolved x-ray diffraction (tr-XD).…”

Section: Introductionmentioning

confidence: 99%

Structural dynamics of laser-irradiated gold nanofilms

et al. 2013

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We performed relativistic ultrafast electron diffraction (UED) measurements of the structural dynamics of photoexcited gold nanofilms and developed an atomistic model, based on the two-temperature molecular dynamics (2T-MD) method, which allows us to make a direct comparison of the time evolutions of measured and calculated Bragg peaks. The quantitative agreement between the temporal evolutions of the experimental and theoretical Bragg peaks at all fluences suggests that the 2T-MD method provides a faithful atomistic representation of the structural evolution of photoexcited gold films. The results reveal the transition between slow heterogeneous melting at low absorbed photon fluence to rapid homogeneous melting at higher fluence and nonthermally driven melting at very high fluence. At high laser fluence, the time evolution of Bragg peaks calculated using the conventional 2T-MD model disagrees with experiment. We show that using an interatomic potential that directly depends on the electron temperature delivers a much better agreement with UED data. Finally, our ab initio calculations of phonon spectra suggest electronic bond softening, if the nanofilms can expand freely under electronic pressure, and bond hardening, if they are constrained in all three dimensions.

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“…In contrast, the so-called nonthermal melting caused by change in the character of electron density distribution (chemical bonds) occurs more rapidly and without significant increase of the ionic temperature. The desire to understand and control such rapid phase transitions has given rise to extensive research including studies on molecular switching [6][7][8][9], nonthermal melting [10][11][12][13], coherent phonon generation [14][15][16][17], metal-to-insulator [18][19][20], magneticto-nonmagnetic [21][22][23], and other ultrafast solid-to-solid [24][25][26] phase transitions. In this paper we focus on solid-tosolid phase transitions in simple metals, particularly tungsten.…”

Section: Introductionmentioning

confidence: 99%

Nonthermal solid-to-solid phase transitions in tungsten

et al. 2014

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The ab initio calculations of phonon dispersions and nonthermal forces along structural deformation paths were used to study nonthermal solid-to-solid phase transitions in photoexcited tungsten. We assumed that electronic excitation can be described by an electronic temperature and demonstrated that nonthermal, i.e., caused purely by electronic excitation, bcc-to-fcc and bcc-to-hcp phase transitions can occur for electronic temperatures between 1.7 and 4.3 eV. These transitions result from soft modes along the line of the Brillouin zone. Structural path calculations at different electronic temperatures indicate that both transitions are likely to take place in nonequilibrium conditions. We further predict that transient fcc and hcp phases of tungsten could be observed for several ps.

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Aperiodic Spin State Ordering of Bistable Molecules and Its Photoinduced Erasing

Cited by 57 publications

References 29 publications

Competing Phases Involving Spin-State and Ligand Structural Orderings in a Multistable Two-Dimensional Spin Crossover Coordination Polymer

Competing Phases Involving Spin-State and Ligand Structural Orderings in a Multistable Two-Dimensional Spin Crossover Coordination Polymer

Structural dynamics of laser-irradiated gold nanofilms

Nonthermal solid-to-solid phase transitions in tungsten

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