Bond-bending and bond-stretching phonons in ferromagneticLa0.7Sr0.3MnO3

Abstract

Longitudinal optical phonons with oxygen character were measured in La0.7Sr0.3MnO3 by inelastic neutron scattering in the (1 0 0) cubic direction and results were compared with shell model predictions. Measurements were performed in several Brillouin zones, which enabled us to identify the eigenvectors independent of the shell model. All major disagreements between model predictions and experimental results are primarily due to the anomalous downward dispersion of the bond-stretching vibration. The main new result is that the rhombohedral distortion of the cubic lattice makes the bond-stretching vibrations interact strongly with bond-bending modes folded into the cubic Brillouin zone.

Evolution of the phonon density of states of LaCoO3over the spin state transition

“…On the other hand, the frequencies determined by optical spectroscopy refer to Raman and IR active phonons at Brillouin zone center. Nevertheless, due to relatively flat dispersion curves of optical phonons 32 , the positions of the observed peaks in INS spectra are well comparable to Raman and IR data of previous studies 15-17 -see Table I. They also show a similar temperature evolution with the course of the spin state transition.…”

Response of Acoustic Phonons to Charge and Orbital Order in the 50% Doped Bilayer ManganiteLaSr2Mn2O7

“…Although the importance of electron-lattice interaction for manganites and, in particular, the CE-type ordered state is based on theoretical considerations [7,8] as well as experimental observations [16], detailed experimental information on phonon dispersions and electron-phonon coupling in manganites is scarce [17][18][19][20]. Here, we present results of an investigation of acoustic phonons in the CE-type COO bilayer manganite La 2À2x Sr 1þ2x Mn 2 O 7 (x ¼ 0:5).…”

“…We chose the double layer manganite despite the large crystallographic unit cell because it lacks structural complications of its pseudocubic counterparts such as twinning and tilted MnO 6 octahedra [19]. As phonon softening is often observed as a precursor to a structural phase transition at the ordering wave vector, our focus was on acoustic phonon dispersions along directions that include wave vectors where superstructure peaks were reported [10,23,24].…”

Continuous-variable quantum teleportation with vacuum-entangled Rindler modes

“…The seminal work of Reznik et al [6] established the field of entanglement harvesting, which considers the swapping of vacuum entanglement onto bi-partite quantum systems, such as Unruh-deWitt detectors, through local interactions. Such harvesting protocols have been applied to spacelike [7] and timelike [8,9] separated detectors, as well as situations involving uniform accelerations [10] and expanding universes [11][12][13][14] A natural question to consider is whether the intrinsic entanglement of spacetime can be utilised as an information-theoretic and physical resource for quantum communication protocols. Previous work by Ralph et al uses observers coupling to the vacuum-entangled modes of a massless scalar field (by operating detectors whose time-dependent energy scaling imitates a uniformly accelerated observer interacting with the Rindler modes [8,9,15]) to implement a quantum key distribution protocol, whilst Reznik has offered proof-of-principle propos- * Electronic address: joshua.foo@uqconnect.edu.au † Electronic address: ralph@physics.uq.edu.au als for dense coding and quantum teleportation protocols through vacuum entanglement swapped onto pairs of stationary, spacelike-separated atoms [16].…”