4 research outputs found
Coexistence of superconductivity and weak anti-localization at KTaO3 (111) interfaces
The intersection of two-dimensional superconductivity and topologically
nontrivial states hosts a wide range of quantum phenomena, including Majorana
fermions. Coexistence of topologically nontrivial states and superconductivity
in a single material, however, remains elusive. Here, we report on the
observation of two-dimensional superconductivity and weak anti-localization at
the TiOx/KTaO3(111) interfaces. A remnant, saturating resistance persists below
the transition temperature as superconducting puddles fail to reach phase
coherence. Signatures of weak anti-localization are observed below the
superconducting transition, suggesting the coexistence of superconductivity and
weak anti-localization. The superconducting interfaces show roughly one order
of magnitude larger weak anti-localization correction, compared to
non-superconducting interfaces, alluding to a relatively large coherence length
in these interfaces
Oxygen vacancy-induced anomalous Hall effect in a non-magnetic oxide
The anomalous Hall effect, a hallmark of broken time-reversal symmetry and
spin-orbit coupling, is frequently observed in magnetically polarized systems.
Its realization in non-magnetic systems, however, remains elusive. Here, we
report on the observation of anomalous Hall effect in nominally non-magnetic
KTaO3. Anomalous Hall effect emerges in reduced KTaO3 and shows an extrinsic to
intrinsic crossover. A paramagnetic behavior is observed in reduced samples
using first principles calculations and quantitative magnetometry. The observed
anomalous Hall effect follows the oxygen vacancy-induced magnetization
response, suggesting that the localized magnetic moments of the oxygen
vacancies scatter conduction electrons asymmetrically and give rise to
anomalous Hall effect. The anomalous Hall conductivity becomes insensitive to
scattering rate in the low temperature limit (T<5 K), implying that the Berry
curvature of the electrons on the Fermi surface controls the anomalous Hall
effect. Our observations describe a detailed picture of many-body interactions,
triggering anomalous Hall effect in a non-magnetic system
Enhanced Critical Field of Superconductivity at an Oxide Interface
The nature of superconductivity and its interplay with strong spin-orbit
coupling at the KTaO3(111) interfaces remains a subject of debate. To address
this problem, we grew epitaxial LaMnO3/KTaO3(111) heterostructures. We show
that superconductivity is robust against the in-plane magnetic field, with the
critical field of superconductivity reaching 25 T in optimally doped
heterostructures. The superconducting order parameter is highly sensitive to
carrier density. We argue that spin-orbit coupling drives the formation of
anomalous quasiparticles with vanishing magnetic moment, providing the
condensate significant immunity against magnetic fields beyond the Pauli
paramagnetic limit. These results offer design opportunities for
superconductors with extreme resilience against magnetic field