Search results for "sähkökentät"
showing 4 items of 4 documents
Structure and dynamics of CaO films: A computational study of an effect of external static electric field
2017
Oxide films play a significant role in a wide range of industrial fields, mostly due to the thickness-dependent variation of their properties. Recently, it has been proposed based on the experimental study that carrier transport in CaO films proceeds via strong phonon excitations with a variable signal depending on the film thickness. In this paper, we report a detailed investigation in the frame of the density functional theory of structural and electronic properties of freestanding and Mo(100)-supported CaO films, as well as phonons therein, as functions of the film thickness and intensity of the external static electric field. Our calculations demonstrate that phonon frequencies negligib…
Control of Molecular Orbital Ordering Using a van der Waals Monolayer Ferroelectric
2022
Two-dimensional (2D) ferroelectric materials provide a promising platform for the electrical control of quantum states. In particular, due to their 2D nature, they are suitable for influencing the quantum states of deposited molecules via the proximity effect. Here, we report electrically controllable molecular states in phthalocyanine molecules adsorbed on monolayer ferroelectric material SnTe. In particular, we demonstrate that the strain and ferroelectric order in SnTe creates a transition between two distinct orbital orders in the adsorbed phthalocyanine molecules. By controlling the polarization of the ferroelectric domain using scanning tunneling microscopy (STM), we have successfully…
Electric-field-controlled reversible order-disorder switching of a metal tip surface
2018
While it is well established that elevated temperatures can induce surface roughening of metal surfaces, the effect of a high electric field on the atomic structure at ambient temperature has not been investigated in detail. Here we show with atomic resolution using in situ transmission electron microscopy how intense electric fields induce reversible switching between perfect crystalline and disordered phases of gold surfaces at room temperature. Ab initio molecular dynamics simulations reveal that the mechanism behind the structural change can be attributed to a vanishing energy cost in forming surface defects in high electric fields. Our results demonstrate how surface processes can be d…
Diffuusiosumukammio taustasäteilyn ja kosmisten hiukkasten havainnollistamisessa
2012
Pro gradu -työssä rakennettiin Jyväskylän yliopiston fysiikan laitokselle säteilyilmaisimena toimiva diffuusiosumukammio jatkuvaan esittelykäyttöön. Tutkimuksessa selvitettiin sumukammion toimintaperiaate sekä erilaiset käyttömahdollisuudet ionisoivan säteilyn havainnollistamisessa. Sumukammion toiminta perustuu ylikylläisen höyryn tiivistymiseen ionisoivan säteilyn kammioon tuottamien ionien ympärille, jolloin varauksellisen hiukkassäteilyn hiukkasten radat näkyvät kammiossa tiivistymisvanoina. Sumukammio kykenee ilmaisemaan suoraan kaikkia varauksellisen hiukkassäteilyn lajeja ja epäsuorasti myös varauksetonta säteilyä sen tuottamien sekundääristen varauksellisten hiukkasten kautta. Tästä…