398 research outputs found
Scaled frequency-dependent transport in the mesoscopically phase-separated colossal magnetoresistive manganite La_{0.625-y}Pr_yCa_{0.375}MnO_3
We address the issue of massive phase separation (PS) in manganite family of
doped Mott insulators through ac conductivity measurements on
LaPrCaMnO (0.375 y 0.275), and
establish applicability of the scaling theory of percolation in the critical
regime of the PS. Measurements of dc resistivity, magnetization (M(T)) and
electron diffraction show incomplete growth of a ferromagnetic (FM) metallic
component on cooling the high temperature charge ordered (CO) phase well below
Curie temperature. The impedance Z(T,f) measured over a frequency
(f) range of 10 Hz to 10 MHz in the critical regime follows a universal scaling
of the form R(T,0)g(f) with 0.86
and the normalized correlation length varying from 1 to 4, suggesting anomalous
diffusion of holes in percolating FM clusters.Comment: 12 pages and 5 figure
Critical current density and vortex pinning in tetragonal FeSSe ()
We report critical current density () in tetragonal FeS single crystals,
similar to iron based superconductors with much higher superconducting critical
temperatures ('s). The is enhanced 3 times by 6\% Se doping. We
observe scaling of the normalized vortex pinning force as a function of reduced
field at all temperatures. Vortex pinning in FeS and FeSSe
shows contribution of core-normal surface-like pinning. Reduced temperature
dependence of indicates that dominant interaction of vortex cores and
pinning centers is via scattering of charge carriers with reduced mean free
path (), in contrast to KFeSe where spatial
variations in () prevails.Comment: 5 pages, 4 figure
The Non-Perturbative Quantum Nature of the Dislocation-Phonon Interaction
Despite the long history of dislocation-phonon interaction studies, there are
many problems that have not been fully resolved during this development. These
include an incompatibility between a perturbative approach and the long-range
nature of a dislocation, the relation between static and dynamic scattering,
and the nature of dislocation-phonon resonance. Here by introducing a fully
quantized dislocation field, the "dislon"[1], a phonon is renormalized as a
quasi-phonon, with shifted quasi-phonon energy, and accompanied by a finite
quasi-phonon lifetime that is reducible to classical results. A series of
outstanding legacy issues including those above can be directly explained
within this unified phonon renormalization approach. In particular, a
renormalized phonon naturally resolves the decades-long debate between dynamic
and static dislocation-phonon scattering approaches.Comment: 5 pages main text, 3 figures, 10 pages supplemental material
Tunable THz Surface Plasmon Polariton based on Topological Insulator-Layered Superconductor Hybrid Structure
We theoretically investigate the surface plasmon polariton (SPP) at the
interface between 3D strong topological insulator (TI) and layered
superconductor-magnetic insulator structure. The tunability of SPP through
electronic doping can be enhanced when the magnetic permeability of the layered
structure becomes higher. When the interface is gapped by superconductivity or
perpendicular magnetism, SPP dispersion is further distorted, accompanied by a
shift of group velocity and penetration depth. Such a shift of SPP reaches
maximum when the magnitude of Fermi level approaches the gap value, and may
lead to observable effects. The tunable SPP at the interface between layered
superconductor and magnetism materials in proximity to TI surface may provide
new insight in the detection of Majorana Fermions.Comment: 6 pages, 4 figure
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