S. A. Trugman

Los Alamos National Laboratory

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Rohit P. Prasankumar

Intellectual Ventures (United States)

Antoinette J. Taylor

Center for Integrated Nanotechnologies

Q. X. Jia

University of British Columbia

Dmitry Yarotski

Los Alamos National Laboratory

Jian‐Xin Zhu

Los Alamos National Laboratory

Richard D. Averitt

University of California, San Diego

A. J. Taylor

Center for Integrated Nanotechnologies

J. Bonča

University of Ljubljana

A. J. Taylor

University of Maryland, College Park

Yaomin Dai

Mahasarakham University

Cooperative Institutions

Los Alamos National Laboratory

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Center for Integrated Nanotechnologies

Chinese Academy of Sciences

Rutgers, The State University of New Jersey

University of California, San Diego

Institute of Physics

University of Chinese Academy of Sciences

National High Magnetic Field Laboratory

Los Alamos Medical Center

Stanford University

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Terahertz emission from YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} thin films via bulk electric quadrupole optical rectification

Jennifer L. W. Siders S. A. Trugman R. J. Houlton F. Garzón A. J. Taylor

The authors describe here the first observation of terahertz emission from unbiased YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} (YBCO) thin films. These films are excited by 150 fs, 1.5 eV and 3.0 eV, optical pulses for a range of temperatures, T, 4 K < T < 300 K and for a range of oxygen doping from optimally-doped ({delta} = 0) to insulating ({delta} = 0.8). They demonstrate that this emission is generated by optical rectification due to the bulk electric quadrupole source term, comprising the first observation of such a source term in terahertz emission.

Optical rectification

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Complex quantum scattering and the breakdown of the quantum Hall effect

Physical Review Letters (1990)

V. Nikos Nicopoulos S. A. Trugman

Quantum potential scattering from abrupt scatterers is studied nonperturbatively in the quantum Hall regime. Complex scattering dynamics including sharp resonances are observed for the first time in this regime. Inter-Landau-level tunneling is strongly enhanced by extended scatterers. The calculated threshold field is in agreement with breakdown experiments. An exact transfer-matrix method and a quasiclassical Wigner-function method are used to extract both amplitudes and phases of the scattering matrix.

10.1103/physrevlett.65.779

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Ultrafast Conductivity Dynamics in Colossal Magnetoresistance Manganites

Physical Review Letters (2001)

Richard D. Averitt A. I. Lobad C. Kwon S. A. Trugman V. K. Thorsmølle

Ultrafast picosecond measurements of optically induced changes in the absolute conductivity (0.4-1.0 THz) of La0.7M0.3MnO3 thin films ( M = Ca, Sr) from 10 K to approximately 0.9 Tc reveal a two-component relaxation. A fast, approximately 2 ps, conductivity decrease arises from an optically induced modification of the effective phonon temperature. The slower component, related to spin-lattice relaxation, has a lifetime that increases upon approaching Tc from below in accordance with an increasing spin specific heat. We show that, for T<

Colossal Magnetoresistance

10.1103/physrevlett.87.017401

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Polaronic signatures in phonon isotopic shifts

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information) (1998)

J. Mustre de León Romeo de Coss A. Rubio‐Ponce A. R. Bishop S. A. Trugman

The effect of O(16) by O(18) isotopic substitution in the excitation spectrum of a model electron-phonon Hamiltonian, previously used to describe the dynamics of the O(4)-Cu(1)-O(4) cluster in YBa{sub 2}Cu{sub 3}O{sub 7}, is presented. This model includes electronic correlations and electron-phonon interactions, exhibiting the presence of polaron tunneling. The calculated isotopic shifts of phonon excitations differ from those found using harmonic or anharmonic potentials, and are consistent results of optical measurements of c-axis phonons. The isotopic substitution changes the dynamics of polaron tunneling and produces a change in the local structure.

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Ultrafast carrier dynamics and radiative recombination in multiferroic BiFeO₃single crystals and thin films

EPJ Web of Conferences (2013)

Yu‐Miin Sheu S. A. Trugman Jie Xiong Y. S. Park S. Lee

We report a detailed comparison of ultrafast carrier dynamics in single crystals and thin films of multiferroic BiFeO3 (BFO). Using degenerate femtosecond optical pump-probe spectroscopy, we find that the observed dynamics are qualitatively similar in both samples. After photoexcitation, electrons relax to the conduction band minimum through electron-phonon coupling, with subsequent carrier relaxation proceeding via various recombination pathways that extend to a nanosecond timescale. Subtle differences observed in our measurements indicate that BFO films have a higher band gap than single crystals. Overall, our results demonstrate that carrier relaxation in BFO is analogous to that in bulk semiconductors.

Photoexcitation

Nanosecond

Thermalisation

10.1051/epjconf/20134103018

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How super is solid He4

Matthias J. Graf Ilya Grigorenko S. A. Trugman Alexander V. Balatsky Z. Nussinov

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Polarization-dependent surface-bulk scattering in the Weyl semimetal NbAs

Conference on Lasers and Electro-Optics (2017)

Yaomin Dai Bing Shen Li‐Juan Zhao Bing Xu Yongkang Luo

Ultrafast optical spectroscopy reveals surface-bulk scattering in the Weyl semimetal NbAs within 50 femtoseconds. The direction of this scattering can be controlled by the pump and probe polarizations, suggesting potential ultrafast device applications.

Weyl semimetal

Surface States

10.1364/cleo_qels.2017.ff1f.4

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Dynamics of Optically Excited Quasiparticles and Coherent Phonons in YBa_2Cu_3O_7-δ

APS March Meeting Abstracts (1998)

A. I. Lobad S. A. Trugman F. Garzón R. J. Houlton T. R. Gosnell

Dynamics

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Mobile Bipolaron

arXiv (Cornell University) (2000)

J. Bonča Tomaž Katrašnik S. A. Trugman

We explore the properties of the bipolaron in a 1D Holstein-Hubbard model with dynamical quantum phonons. Using a recently developed variational method combined with analytical strong coupling calculations, we compute correlation functions, effective mass, bipolaron isotope effect and the phase diagram. The two site bipolaron has a significantly reduced mass and isotope effect compared to the on-site bipolaron, and is bound in the strong coupling regime up to twice the Hubbard U naively expected. The model can be described in this regime as an effective t-J-V model with nearest neighbor repulsion. These are the most accurate bipolaron calculations to date.

Bipolaron

10.48550/arxiv.cond-mat/0001325

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Coherent optical and acoustic phonon generation correlated with the charge-ordering phase transition inLa1−xCaxMnO3

Physical Review B (2005)

Dong Woo Lim V. K. Thorsmølle Richard D. Averitt Q. X. Jia K. H. Ahn

We have observed coherent optical and acoustic phonon generation, which are strongly coupled to the charge-ordering (CO) transition in (, 0.58) using femtosecond optical pump-probe spectroscopy. Coherent optical phonons, observed at low temperatures, disappear above the charge-ordering temperature , while coherent acoustic phonons display the opposite behavior, disappearing gradually below . Coherent optical phonons are generated by the displacive excitation mechanism where their coupling to the photoexcited charge carriers is enhanced by the structural change corresponding to the CO phase transition. The oscillation frequency for the coherent acoustic phonon depends on the probe wavelength, which is consistent with the propagating strain pulse mechanism. The dramatic change of lattice constants across the charge-ordering transition explains the overall temperature dependence of the coherent acoustic phonon amplitude.

Oscillation (cell signaling)

Charge ordering

10.1103/physrevb.71.134403

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Citations (41)