Fourfold Symmetric Superconductivity in Spinel Oxide LiTi₂O₄(001) Thin Films

Abstract

The charge frustration with the mixed-valence state inherent to LiTi2O4, which is found to be the only oxide superconductor with spinel structure, is the impetus for paying special attention to unveil the underlying intriguing superconducting properties. Here, we report a pronounced fourfold rotational symmetry of the superconductivity in high-quality single-crystalline LiTi2O4(001) thin films. Both the magnetoresistivity and upper critical field under an applied magnetic field manifest striking fourfold oscillations deep inside the superconducting state, whereas the anisotropy vanishes in the normal state, demonstrating that it is an intrinsic property of the superconducting phase. We attribute this behavior to the unconventional d-wave superconducting Cooper pairs with the irreducible representation of Eg protected by the Oh point group in cubic LiTi2O4. Our findings show the nontrivial character of the pairing interaction in a three-dimensional spinel oxide superconductor.

Spontaneous rotational symmetry breaking in KTaO3 heterointerface superconductors

“…4 b) such that for the φ value where superconductivity is hardest to suppress, μ 0 H is the largest and R s is the lowest (Fig. 4 b, d), as expected from our intuitions 50 – 52 . Since μ 0 H achieves its maximum for the field applied perpendicular to the main crystallographic axis, and minimum for the direction along the main crystallographic axis (see Figs.…”

“…4 a and Supplementary Fig. 11) , we could further rule out the possibilities of extrinsic contributions, such as the magnetic field induced Lorentz force effect 50 and the Fermi surface inherent to the KTaO 3 with respect to the underlying threefold lattice symmetry 26 (Fig. 1 c and Supplementary Fig.…”

Coexistence of Ferromagnetism and Superconductivity at KTaO3 Heterointerfaces

“…On the other hand, X-ray diffraction (XRD) exposes the absence of epitaxial Bragg reflection peaks in both the LaAlO 3 and YAlO 3 thin films (see Figure S2, YAlO 3 presented in ref ), confirming the deposition of an amorphous phase for both the LaAlO 3 and YAlO 3 thin films on the KTaO 3 (111) substrates. These results align well with previous investigations. − Subsequently, we conduct electrical transport measurements on the devices of the as-grown thin films arranged in Hall bar configurations (see Figure a). , …”

Metal–air batteries for powering robots

“…Spinel and perovskite oxides, with their adjustable chemical composition, diverse structures, high conductivity, and ease of preparation, have been widely studied. 97,98 Dong et al 99 prepared CuMnO 2 nanosheets via a hydrothermal method, which effectively improved the ORR activity due to their unique structure and good stability. Discharge tests revealed the excellent stability and durability in alkaline solutions and stable operating voltage in neutral solutions when using this catalyst.…”