Fermi surface in La-based cuprate superconductors from Compton scattering imaging

Abstract

Compton scattering provides invaluable information on the underlying Fermi surface (FS) and is a powerful tool complementary to angle-resolved photoemission spectroscopy and quantum oscillation measurements. Here we perform high-resolution Compton scattering measurements for La2−xSrxCuO4 with x = 0.08 (Tc = 20 K) at 300 K and 150 K, and image the momentum distribution function in the two-dimensional Brillouin zone. We find that the observed images cannot be reconciled with the conventional hole-like FS believed so far. Instead, our data imply that the FS is strongly deformed by the underlying nematicity in each CuO2 plane, but the bulk FSs recover the fourfold symmetry. We also find an unusually strong temperature dependence of the momentum distribution function, which may originate from the pseudogap formation in the presence of the reconstructed FSs due to the underlying nematicity. Additional measurements for x = 0.15 and 0.30 at 300 K suggest similar FS deformation with weaker nematicity, which nearly vanishes at x = 0.30.

Designing high-TC superconductors with BCS-inspired screening, density functional theory, and deep-learning

“…S9. The shape of the Fermi-surface depicts the electron motion inside a material 62 . In earlier works 63 related to MgB 2 type compounds, the shape of the Fermi surface helped understand the mechanism of superconductivity in such compounds.…”

Gapped Collective Charge Excitations and Interlayer Hopping in Cuprate Superconductors

“…1(a)]. In contrast, other studies assume that t z is negligibly small compared to t and t, which is in line with a smaller interlayer hopping evaluated from experiments [39,41]. Thus, new methods for a reliable determination of the contentious parameter t z are highly desirable.…”

“…The interlayer tunneling mechanism is most effective when coherent single particle hopping between adjacent CuO 2 planes is inhibited in the normal-state [27]. Nevertheless, coherent normal-state c-axis transport properties were detected in various experiments on overdoped cuprates [36][37][38], while in lightly doped cuprates it is challenging to assess whether interlayer hopping is small or absent [36,39]. In fact, the extraction of accurate values of the interlayer hopping integral t z from experimental data has proven difficult not only for lightly but also for overdoped cuprates [37,[40][41][42][43][44].…”

“…More specifically, our approach combining RIXS and t-J-V model calculations enables the extraction of robust values of t z in cuprates -possibly even in lightly doped cuprates which has not been accomplished with other experimental methods [39][40][41][42][43]. Moreover, we anticipate that our methodology will be applicable to other materials, including layered 2D materials and van der Waals heterostructures [78][79][80], as well as the newly discovered infinite-layer nickelate superconductors [81][82][83], which might possess even larger interlayer hoppings than SLCO [71].…”