Coherent magnon and acoustic phonon dynamics in tetragonal and rare-earth-doped BiFeO<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mn>3</mml:mn></mml:msub></mml:math>multiferroic thin films

Doig, K. I.; Aguesse, Frédéric; Axelsson, Anna‐Karin; Alford, Neil McN.; Nawaz, S.; Palkar, V. R.; Jones, S. P. P.; Johnson, Roger A.; Synowicki, R. A.; Lloyd‐Hughes, James

doi:10.1103/physrevb.88.094425

Cited by 22 publications

(29 citation statements)

References 43 publications

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“…However, the high frequency (75 GHz) feature cannot result from the acoustic phonon mechanism, as the oscillation is present at all time delays. In a previous study of magnons in BiFeO 3 thin films a mode at a comparable frequency was found to disappear above the Néel temperature37. Both the PTFO films reported here and the BiFeO 3 films previously studied37 had LaAlO 3 substrates, and therefore have comparable in-plane lattice constants and Fe-Fe distances (assuming that there are regions of the PTFO samples with Fe ions in adjacent cells).…”

Section: Resultssupporting

confidence: 60%

“…Time-resolved reflectivity thus permits electronic generation and relaxation processes to be examined. Further, coherent oscillations in Δ R can result from magnons in multiferroics3637. The observed transients for the PTFO films (Fig.…”

Section: Resultsmentioning

confidence: 86%

“…While Δ R appeared as in curve (ii) in the majority of positions, in a smaller number of cases either no oscillations [curve (i)] or oscillations with a 180° phase shift [curve (iii)] were observed. Acoustic phonons can contribute to Δ R for oxide thin films37. The oscillation frequency depends upon the acoustic phonon velocity, and thus changes when the acoustic pulse propagates from the film to the substrate.…”

Section: Resultsmentioning

confidence: 99%

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Structural, optical and vibrational properties of self-assembled Pbn+1(Ti1−xFex)nO3n+1−δ Ruddlesden-Popper superstructures

Doig

Peters

Nawaz

et al. 2015

Sci Rep

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Bulk crystals and thin films of PbTi1−xFexO3−δ (PTFO) are multiferroic, exhibiting ferroelectricity and ferromagnetism at room temperature. Here we report that the Ruddlesden-Popper phase Pbn+1(Ti1−xFex)nO3n+1−δ forms spontaneously during pulsed laser deposition of PTFO on LaAlO3 substrates. High-resolution transmission electron microscopy, x-ray diffraction and x-ray photoemission spectroscopy were utilised to perform a structural and compositional analysis, demonstrating that and . The complex dielectric function of the films was determined from far-infrared to ultraviolet energies using a combination of terahertz time-domain spectroscopy, Fourier transform spectroscopy, and spectroscopic ellipsometry. The simultaneous Raman and infrared activity of phonon modes and the observation of second harmonic generation establishes a non-centrosymmetric point group for Pbn+1(Ti0.5Fe0.5)nO3n+1−δ, a prerequisite for (but not proof of) ferroelectricity. No evidence of macroscopic ferromagnetism was found in SQUID magnetometry. The ultrafast optical response exhibited coherent magnon oscillations compatible with local magnetic order, and additionally was used to study photocarrier cooling on picosecond timescales. An optical gap smaller than that of BiFeO3 and long photocarrier lifetimes may make this system interesting as a ferroelectric photovoltaic.

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Section: Resultssupporting

confidence: 60%

Section: Resultsmentioning

confidence: 86%

Section: Resultsmentioning

confidence: 99%

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Structural, optical and vibrational properties of self-assembled Pbn+1(Ti1−xFex)nO3n+1−δ Ruddlesden-Popper superstructures

Doig

Peters

Nawaz

et al. 2015

Sci Rep

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“…From these we obtain C 11 = 58(6) GPa, C 44 = 42(4) GPa, C 12 = 17(2) GPa, and the bulk modulus B = 1 3 (C 11 + 2C 12 ) = 31(3) GPa. We note that the room temperature values of the longitudinal elastic constant C 11 derived from previous experimental 19,23,24 and theoretical work 25,26 on BiFeO 3 are highly inconsistent. The value of C 11 ranges from ≈ 60 GPa (our neutron measurements), to ≈ 125 GPa (ultrasonic measurements), to ≈ 207 GPa (x-ray inelastic measurements).…”

Section: Resultsmentioning

confidence: 64%

Neutron inelastic scattering measurements of low-energy phonons in the multiferroicBiFeO3

Schneeloch

Wen

et al. 2015

Phys. Rev. B

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We present neutron inelastic scattering measurements of the low-energy phonons in single crystal BiFeO3. The dispersions of the three acoustic phonon modes (LA along [100], TA1 along [010] and TA2 along [110]) and two low energy optic phonon modes (LO and TO1) have been mapped out between 300 K and 700 K. Elastic constants are extracted from the phonon measurements. The energy linewidths of both TA phonons at the zone boundary clearly broaden when the system is warmed toward the magnetic ordering temperature TN = 640 K. This suggests that the magnetic order and low-energy lattice dynamics in this multiferroic material are coupled.

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“…17 The rapid photo-induced mechanical stress results in the excitation of coherent acoustic phonons and magnons. 18,19 The dynamics of photo-induced strain was directly and quantitatively measured in a synchrotron-based ultrafast X-ray diffraction. 20 One of the most straightforward implementations of ultrafast spectroscopy is the hot electron transient relaxation following the photo-excitation.…”

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confidence: 99%

Temperature dependent photoexcited carrier dynamics in multiferroic BiFeO3 film: A hidden phase transition

Zhang¹,

Jin²,

Pan³

et al. 2014

Applied Physics Letters

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The ultrafast carrier dynamics of the multiferroic BiFeO3 film in a broad temperature range is investigated using optical pump-probe spectroscopy. The photoexcited electrons release their energy with optical phonons emission through electron-phonon coupling in about 1 ps. The following intermediate process is identified as dynamical spin-lattice coupling in several picoseconds. Furthermore, the peak values of the optical reflectivity and the time constants of carrier relaxation channels show significant changes while the temperature varies from 137.5 K to around 195 K, this aligns with the previously reported hidden phase transition. Our study demonstrates that ultrafast spectroscopy is a sensitive method to look into the dynamical interactions among the on-site high-energy electrons accumulated in the p conduction band of Bi, coherent optical phonon, as well as the spin degree of freedom. These features play crucial roles in the characterization of phase transitions.

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Coherent magnon and acoustic phonon dynamics in tetragonal and rare-earth-doped BiFeO3multiferroic thin films

Cited by 22 publications

References 43 publications

Structural, optical and vibrational properties of self-assembled Pbn+1(Ti1−xFex)nO3n+1−δ Ruddlesden-Popper superstructures

Structural, optical and vibrational properties of self-assembled Pbn+1(Ti1−xFex)nO3n+1−δ Ruddlesden-Popper superstructures

Neutron inelastic scattering measurements of low-energy phonons in the multiferroicBiFeO3

Temperature dependent photoexcited carrier dynamics in multiferroic BiFeO3 film: A hidden phase transition

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