Now showing items 1-9 of 9

    • Electronic structure of silicon-based nanostructures 

      Guzmán Verri, Gian Giacomo; Lew Yan Voon, Lok Chong (2007-08-30)
      We have developed a unifying tight-binding Hamiltonian that can account for the electronic properties of recently proposed Si-based nanostructures, namely, Si graphene-like sheets and Si nanotubes. We considered the sp3s∗ ...
    • Landau theory and giant room-temperature barocaloric effect 

      Corrales Salazar, A.; Brierley, Richard T.; Littlewood, Peter B.; Guzmán Verri, Gian Giacomo (2017-10-17)
      The structural phase transitions of MF3 (M = Al, Cr, V, Fe, Ti, Sc) metal trifluorides are studied within a simple Landau theory consisting of tilts of rigid MF6 octahedra associated with soft antiferrodistortive optic ...
    • Large isotropic negative thermal expansion above a structural quantum phase transition 

      Handunkanda, Sahan U.; Curry, Erin B.; Voronov, Vladimir; Said, Ayman H.; Guzmán Verri, Gian Giacomo; Brierley, Richard T.; Littlewood, Peter B.; Hancock, Jason N. (2015-10-01)
      Perovskite structured materials contain myriad tunable ordered phases of electronic and magnetic origin with proven technological importance and strong promise for a variety of energy solutions. An always-contributing ...
    • Negative Thermal Expansion in Open Perovskites near the Precipice of Structural Stability 

      Occhialini, Connor A.; Guzmán Verri, Gian Giacomo; Handunkanda, Sahan U.; Hancock, Jason N. (2018)
      Negative thermal expansion (NTE) describes the anomalous propensity of materials to shrink when heated. Since its discovery, the NTE effect has been found in a wide variety of materials with an array of magnetic, electronic ...
    • Negative thermal expansion near two structural quantum phase transitions Connor 

      Guzmán Verri, Gian Giacomo; Hancock, Jason N. (2017-12-18)
      Recent experimental work has revealed that the unusually strong, isotropic structural negative thermal expansion in cubic perovskite ionic insulator ScF3 occurs in excited states above a ground state tuned very near a ...
    • Quantum Ferroelectric Instabilities in Superconducting SrTiO3 

      Arce Gamboa, José Rafael; Guzmán Verri, Gian Giacomo (2018)
      We examine the effects of strain and cation substitution on the superconducting phase of polar semiconductors near a ferroelectric quantum phase transition with a model that combines a strong coupling theory of ...
    • Random Electric Field Instabilities of Relaxor Ferroelectrics 

      Guzmán Verri, Gian Giacomo; Arce Gamboa, José Rafael (2017-06-13)
      Relaxor ferroelectrics are complex oxide materials which are rather unique to study the effects of compositional disorder on phase transitions. Here, we study the effects of quenched cubic random electric fields on the ...
    • Structure factor of a relaxor ferroelectric 

      Guzmán Verri, Gian Giacomo; Varma, Chandra M. (2015-04-14)
      We study a minimal model for a relaxor ferroelectric including dipolar interactions, and short-range harmonic and anharmonic forces for the critical modes as in the theory of pure ferroelectrics together with quenched ...
    • Why is the electrocaloric effect so small in ferroelectrics? 

      Guzmán Verri, Gian Giacomo; Littlewood, Peter B. (2016-05-19)
      Ferroelectrics are attractive candidate materials for environmentally friendly solid state refrigeration free of greenhouse gases. Their thermal response upon variations of external electric fields is largest in the vicinity ...