Dynamic Stimulation of Superconductivity With Resonant Terahertz Ultrasonic Waves

Kadin, Alan M.; Kaplan, Steven B.

doi:10.1109/tasc.2017.2654858

Cited by 4 publications

(3 citation statements)

References 45 publications

(40 reference statements)

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“…It is worth underlining that in this work for the first time graphene was used for pumping superconducting films by ZA phonons. In fact, the enhancement of superconductivity with terahertz phonons was previously theoretically proposed [68,[75][76][77] and experimentally realized [78][79][80][81][82][83][84][85] by generating acoustic phonons with optical excitation in resonance with out-of-plane phonons [82], terahertz electromagnetic irradiation [83] or ultrafast laser pulses [84,85].…”

Section: Discussionmentioning

confidence: 99%

Superconducting critical temperature and softening of the phonon spectrum in ultrathin nb- and nbn/graphene hybrids

Prischepa¹,

Kushnir²,

Cirillo³

et al. 2021

Supercond. Sci. Technol.

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Superconductivity is studied in hybrids consisting of ultrathin superconducting film/few layer graphene. Two different superconductors were used at this purpose, Nb and NbN. An increase of the superconducting critical temperature, T c , is observed when graphene is put into contact with Nb. The largest increase is obtained for the thinnest Nb layer, which has a T c 8% larger with respect to the single Nb film. In the case of NbN the effect is not so pronounced. Experimental data are discussed by considering the possible modification of the phonon spectrum in the superconductor due to the presence of the graphene. Within an elementary one-dimensional model based on an elastic coupling between nearestneighbor atoms, we demonstrate that the phonon spectrum in the superconductor is modified at low energies with the subsequent enhancement of the effective electron-phonon coupling constant. While the strong oscillating nature of the electron-phonon interaction,  2 (), in NbN could lead to the insensitivity of T c on the low-energy phonons generated by the graphene, the almost constant behavior of  2 () in Nb favors the increase of the superconducting critical temperature.

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Section: Discussionmentioning

confidence: 99%

Superconducting critical temperature and softening of the phonon spectrum in ultrathin nb- and nbn/graphene hybrids

Prischepa¹,

Kushnir²,

Cirillo³

et al. 2021

Supercond. Sci. Technol.

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“…In the context of studying transport through low-dimensional structures, the close relationship between the Landauer and Kubo formalisms, enables the ports of a sample to be probed by lithographically fabricated leads. Surface acoustic wave transducers oriented at different angles could be used to probe the way in which elastic waves interact with normal metals and superconductors [47]. We are particularly interested in using EAI for probing spin waves, where, unlike FerroMagnetic Resonance, it is not necessary to sweep the field in order to infer modal content from spectra.…”

Section: Resultsmentioning

confidence: 99%

Probing quantum correlation functions through energy-absorption interferometry

2017

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An interferometric technique is proposed for determining the spatial forms of the individual degrees of freedom through which a many body system can absorb energy from its environment. The method separates out the coherent excitations present at any given frequency; it is not necessary to infer modal content from spectra. The system under test is excited with two external sources, which create generalized forces, and the fringe in the total power dissipated is measured as the relative phase between the sources is varied. If the complex fringe visibility is measured for different pairs of source locations, the anti-Hermitian part of the complex-valued non-local correlation tensor can be determined, which can then be decomposed to give the natural dynamical modes of the system and their relative responsivities. If each source in the interferometer creates a different kind of force, the spatial forms of the individual excitations that are responsible for cross-correlated response can be found. The technique is a generalization of holography because it measures the state of coherence to which the system is maximally sensitive. It can be applied across a wide range of wavelengths, in a variety of ways, to homogeneous media, thin films, patterned structures, and to components such as sensors, detectors and energy harvesting absorbers. arXiv:1609.03174v1 [quant-ph]

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“…Together, this has ensured the technological relevance of the material; well adapted for exploitation in ultrasonic transducers 3,4 , ceramic capacitors and actuators 5 . More exotically, PZT has been proposed for use in potential piezoelectricity-induced room temperature superconductors where a supercurrent is induced along a metal/piezoelectric interface 6,7 . For these applications, it is most common to consider PZT at around x ≈ 0.52 8,9 in the region near the morphotropic phase boundary (MPB).…”

Section: Introductionmentioning

confidence: 99%

First-principles soft-mode lattice dynamics of PbZr0.5Ti0.5O3 and shortcomings of the virtual crystal approximation

Baker

Bowler

2019

Phys. Rev. B

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A comparative study between PbTiO3, PbZrO3, and the solid solution PbZr0.5Ti0.5O3 is performed on the soft mode lattice dynamics within the first Brillouin Zone. We consider the six unique B-site orderings for PbZr0.5Ti0.5O3 representable within the 2×2×2 primitive perovskite supercell as well as the virtual crystal approximation (VCA) to extract the phonon dispersion relations of a high-symmetry cubic-constrained form using density functional perturbation theory. We find that the most unstable modes in the rock-salt ordered structure and the VCA, like pure PbZrO3, are antiferrodistortive (AFD) whilst lower symmetry arrangements are dominated by Γ-point ferroelectric (FE) instabilities like pure PbTiO3. Despite similarities in the phonon dispersion relations between the rock-salt ordered supercell and the VCA, the character of modes at high symmetry points are found to be different. In particular, the a 0 a 0 c − & a 0 a 0 c + AFD instabilities of the rocksalt ordering are replaced with a − b − c − & a + b + c + instabilities within the VCA. Such a rotation pattern is not seen in any of the supercell-based calculations thus serving as a quantitative example of the inability of the method to represent accurately local structural distortions. Single modes are found exhibiting dual order parameters. At the zone centre, some arrangements show mixed FE & antipolar soft modes (due to Pb motion tansverse to the polar axis) and at long wavelengths all arrangements have soft modes of a mixed antipolar & AFD character. These are described with direct analysis of the eigendisplacements.

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Dynamic Stimulation of Superconductivity With Resonant Terahertz Ultrasonic Waves

Cited by 4 publications

References 45 publications

Superconducting critical temperature and softening of the phonon spectrum in ultrathin nb- and nbn/graphene hybrids

Superconducting critical temperature and softening of the phonon spectrum in ultrathin nb- and nbn/graphene hybrids

Probing quantum correlation functions through energy-absorption interferometry

First-principles soft-mode lattice dynamics of PbZr0.5Ti0.5O3 and shortcomings of the virtual crystal approximation

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