37 research outputs found
Superconductivity in a new hexagonal high entropy alloy
High entropy alloys (HEAs) are the new class of materials with an attractive
combination of tunable mechanical and physicochemical properties. They
crystallize mainly in cubic structures, however, for practical applications,
HEAs with hexagonal close-packed (hcp) structure are highly desirable in
connection to their in general high hardness. Herein, we report the synthesis,
structure and detailed superconducting properties of
ReNbTiZrHf-the first hexagonal
superconducting high entropy alloy (HEA) composed of five randomly distributed
transition-metals. Combination of room temperature precession electron
diffraction, precession electron diffraction tomography and powder X-ray
diffraction is utilized to determine the room temperature crystal structure.
Transport, magnetic and heat capacity measurements show that the material is a
type-II superconductor with the bulk superconducting transition at =
4.4 K, lower critical field (0) = 2.3 mT and upper critical field
(0) = 3.6 T. Low-temperature specific heat measurement indicates that
ReNbTiZrHf is a phonon-mediated
superconductor in the weak electron-phonon coupling limit with a normalized
specific heat jump = 1.32. Further,
hexagonal to cubic structural transition is observed by lowering the valence
electron counts and follows crystalline-like behaviour.Comment: 6 Pages, 9 Figures. arXiv admin note: text overlap with
arXiv:1804.1009
Generation of strain-induced pseudo-magnetic field in a doped type-II Weyl semimetal
In Weyl semimetals, there is an intriguing possibility of realizing a
pseudo-magnetic field in presence of small strain due to certain special cases
of static deformations. This pseudo-magnetic field can be large enough to form
quantized Landau levels and thus become observable in Weyl semimetals. In this
paper, we experimentally show the emergence of a pseudo-magnetic field (~ 3
Tesla) by Scanning Tunneling Spectroscopy (STS) on the doped Weyl semimetal
Re-MoTe2, where distinct Landau level oscillations in the tunneling conductance
are clearly resolved. The crystal lattice is intrinsically strained where large
area STM imaging of the surface reveals differently strained domains where
atomic scale deformations exist forming topographic ripples with varying
periodicity in the real space. The effect of pseudo-magnetic field is clearly
resolved in areas under maximum strain.Comment: 6 pages, 4 figure