03036nas a2200697 4500008004100000022001300041245009300054210006900147300001200216490000700228520111100235653001201346653002201358653002301380653001301403653001901416653001401435653002701449653002401476653002001500653003001520653002101550653002201571653002501593653003301618653002701651653002201678653001101700653001001711653002401721653001101745653001501756653002201771653002201793653001201815653001401827653002501841653001501866653002501881653002001906653001301926100002101939700001601960700001601976700001701992700002002009700001802029700001502047700001602062700001502078700001202093700002402105700001602129700001702145700001702162700001802179700001702197700002402214700002002238856008002258 2014 eng d a1476112200aCrossover from incoherent to coherent phonon scattering in epitaxial oxide superlattices0 aCrossover from incoherent to coherent phonon scattering in epita a168-1720 v133 aElementary particles such as electrons or photons are frequent subjects of wave-nature-driven investigations, unlike collective excitations such as phonons. The demonstration of wave-particle crossover, in terms of macroscopic properties, is crucial to the understanding and application of the wave behaviour of matter. We present an unambiguous demonstration of the theoretically predicted crossover from diffuse (particle-like) to specular (wave-like) phonon scattering in epitaxial oxide superlattices, manifested by a minimum in lattice thermal conductivity as a function of interface density. We do so by synthesizing superlattices of electrically insulating perovskite oxides and systematically varying the interface density, with unit-cell precision, using two different epitaxial-growth techniques. These observations open up opportunities for studies on the wave nature of phonons, particularly phonon interference effects, using oxide superlattices as model systems, with extensive applications in thermoelectrics and thermal management. © 2014 Macmillan Publishers Limited. All rights reserved.10aArticle10aCalcium compounds10acalcium derivative10aChemical10achemical model10achemistry10aCollective excitations10aComputer simulation10acrystallization10adensity functional theory10aEpitaxial growth10aInterface density10aInterference effects10aLattice thermal conductivity10aMacroscopic properties10aMaterials testing10amodels10aoxide10aOxide superlattices10aoxides10aPerovskite10aPerovskite oxides10aPhonon scattering10aPhonons10aradiation10aRadiation scattering10ascattering10aThermal conductivity10aThermoelectrics10atitanium1 aRavichandran, J.1 aYadav, A.K.1 aCheaito, R.1 aRossen, P.B.1 aSoukiassian, A.1 aSuresha, S.J.1 aDuda, J.C.1 aFoley, B.M.1 aLee, C.-H.1 aZhu, Y.1 aLichtenberger, A.W.1 aMoore, J.E.1 aMuller, D.A.1 aSchlom, D.G.1 aHopkins, P.E.1 aMajumdar, A.1 aRamesh, Ramamoorthy1 aZurbuchen, M.A. uhttps://rameshlab.lbl.gov/publications/crossover-incoherent-coherent-phonon01432nas a2200205 4500008004100000022001300041245006400054210006300118490000700181520081700188100002101005700001601026700001801042700001701060700001601077700001601093700001701109700002401126856007601150 2011 eng d a1098012100aTuning the electronic effective mass in double-doped SrTiO30 aTuning the electronic effective mass in doubledoped SrTiO30 v833 aWe elucidate the relationship between effective mass and carrier concentration in an oxide semiconductor controlled by a double-doping mechanism. In this model oxide system, Sr1-xLaxTiO 3-δ, we can tune the effective mass ranging from 6 to 20m e as a function of filling (carrier concentration) and the scattering mechanism, which are dependent on the chosen lanthanum- and oxygen-vacancy concentrations. The effective mass values were calculated from the Boltzmann transport equation using the measured transport properties of thin films of Sr1-xLaxTiO3-δ. We show that the effective mass decreases with carrier concentration in this large-band-gap, low-mobility oxide, and this behavior is contrary to the traditional high-mobility, small-effective-mass semiconductors. © 2011 The American Physical Society.1 aRavichandran, J.1 aSiemons, W.1 aScullin, M.L.1 aMukerjee, S.1 aHuijben, M.1 aMoore, J.E.1 aMajumdar, A.1 aRamesh, Ramamoorthy uhttps://rameshlab.lbl.gov/publications/tuning-electronic-effective-mass