Prof. Francisco Javier Manjón

Instituto de Diseño y Fabricación (IDF)

Prof. Francisco Javier Manjón

Instituto de Diseño y Fabricación (IDF)

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Academic Career Length

30Years (1997-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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30 March 2004 in Physical Review B

Journal Article

Pressure dependence of the lattice dynamics of ZnO: Anab initioapproach

J. Serrano

A. H. Romero

Francisco Javier Manjón

R. Lauck

M. Cardona

A. Rubio

We have performed first-principles calculations of the electronic structure of ZnO, and applied them to the determination of structural and lattice-dynamical properties and their dependence on pressure. The dynamical matrices have been obtained for the wurtzite, zinc-blende, and rocksalt modifications with several lattice parameters optimized for pressures up to 12 GPa. These matrices are employed to calculate the one-phonon densities of states (DOS) and the two-phonon DOS associated with either sums or differences of phonons. These results provide the essential tools to analyze the effect of isotope-induced mass disorder and anharmonicity on phonon linewidths, which we discuss here and compare with experimental data from Raman spectroscopy, including first- and second-order spectra. Agreement of calculated properties with experimental results improves considerably when the renormalization due to anharmonicity is subtracted from the experimental data.

16 February 2005 in Journal of Applied Physics

Journal Article

Silent Raman modes in zinc oxide and related nitrides

Francisco Javier Manjón

B. Marí

J. Serrano

Aldo H. Romero

Anomalous Raman modes have been reported in several recent papers dealing with doped- and undoped-ZnO layers grown by different methods. Most of these anomalous Raman modes have been attributed to local vibrational modes of impurities or defects. However, we will show that most of the observed modes correspond to wurtzite-ZnO silent modes allowed by the breakdown of the translational crystal symmetry induced by defects and impurities.

1 May 2008 in Progress in Materials Science

Journal Article

Pressure effects on the structural and electronic properties of ABX4 scintillating crystals

Daniel Errandonea

Francisco Javier Manjón

7 February 2003 in Physical Review Letters

Journal Article

Dispersive Phonon Linewidths: The

E_{2}

Phonons of ZnO

J. Serrano

Francisco Javier Manjón

A. H. Romero

F. Widulle

R. Lauck

M. Cardona

Phonon linewidths can exhibit a large variation when either pressure or isotopic masses are changed. These effects yield detailed information about the mechanisms responsible for linewidths and lifetimes, e.g., anharmonicity or isotopic disorder. We report Raman measurements of the linewidth of the upper

E_{2}

phonons of ZnO crystals with several isotopic compositions and their dependence on pressure. Changes by a factor of 12 are observed at a given temperature. Comparison with calculated densities of one-phonon states, responsible for isotope scattering, and of two-phonon states, responsible for anharmonic decay, yields a consistent picture of these phenomena. Isotopic disorder broadening by

7 {c m}^{- 1}

is found in samples with mixed

{}^{16}O - {}^{18}O

content, whereas the anharmonic processes involve decay into sums and differences of two phonons.

8 November 2005 in Physical Review B

Journal Article

High-pressure structural study of the scheelite tungstates

{CaWO}_{4}

and

{SrWO}_{4}

Daniel Errandonea

Julio Pellicer Porres

Francisco Javier Manjón

Alfredo Segura

Ch. Ferrer-Roca

G. Aquilanti

Angle-dispersive x-ray-diffraction and x-ray-absorption near-edge structure measurements have been performed on

{CaWO}_{4}

and

{SrWO}_{4}

up to pressures of approximately 20 GPa. Both materials display similar behavior in the range of pressures investigated in our experiments. As in the previously reported case of

{CaWO}_{4}

, under hydrostatic conditions

{SrWO}_{4}

undergoes a pressure-induced scheelite-to-fergusonite transition around 10 GPa. Our experimental results are compared to those found in the literature and are further supported by ab initio total-energy calculations, from which we also predict the instability at larger pressures of the fergusonite phases against an orthorhombic structure with space group Cmca. Finally, a linear relationship between the charge density in the

A O_{8}

polyhedra of

A B O_{4}

scheelite-related structures and their bulk modulus is discussed and used to predict the bulk modulus of other materials, like hafnon.

14 July 2003 in Applied Physics Letters

Journal Article

Optical properties and electronic structure of rock-salt ZnO under pressure

Alfredo Segura

Juan Angel Sans

Francisco Javier Manjón

Alfonso Muñoz

M. J. Herrera-Cabrera

This letter reports on the pressure dependence of the optical absorption edge of ZnO in the rock-salt phase, up to 20 GPa. Both vapor-phase monocrystals and pulsed-laser-deposition thin films on mica have been investigated. Rock-salt ZnO is shown to be an indirect semiconductor with a band gap of 2.45±0.15 eV, whose pressure coefficient is very small. At higher photon energies, a direct transition is observed (4.6 eV at 10 GPa), with a positive pressure coefficient (around 40±3 meV/GPa between 5 and 19 GPa). These results are interpreted on the basis of first-principles electronic band structure calculations.

About Me

Francisco Javier Manjón received his Ph.D. in Physics from the Universitat de València (Spain) in 1999. This was followed by a postdoctoral research stay at the Max Planck Institute for Solid State Research in Stuttgart (Germany) thanks to a Marie Curie Fellowship of the European Union. In 2001, he joined the Universitat Politècnica de València (UPV) in Spain as Assistant Professor of the Applied Physics Department. Since 2007, he has been the main researcher of the group for the study of materials under extreme pressure and temperature conditions (EXTREMAT) at the Instituto para el Diseño y la Fabricación Automatizada (IDF) of UPV. His research interests include the experimental and theoretical study of structural, vibrational, electronic, and chemical properties of materials both under normal and extreme temperature and pressure conditions with special emphasis on minerals and materials for optoelectronic applications. Since 2017, he has been a full professor of Applied Physics at UPV, and since 2020, he has been the coordinator of the High-Pressure Spanish Network (MALTA Consolider Team). In 2023 and 2024, he developed the theory of multicenter bonding, which describes the origin and formation mechanisms of electron-rich and electron-deficient multicenter bonds in molecules and solids.

Prof. Francisco Javier Manjón

Prof. Francisco Javier Manjón

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