  Stacking two-dimensional van der Waals (vdW) materials rotated with respect
to each other show versatility for the study of exotic quantum phenomena.
Especially, anisotropic layered materials have great potential for such
twistronics applications, providing high tunability. Here, we report
anisotropic superconducting order parameters in twisted Bi2Sr2CaCu2O8+x
(Bi-2212) vdW junctions with an atomically clean vdW interface, achieved using
the microcleave-and-stack technique. The vdW Josephson junctions with twist
angles of 0{\deg} and 90{\deg} showed the maximum Josephson coupling, which was
comparable to that of intrinsic Josephson (IJ) junctions in the bulk crystal.
As the twist angle approaches 45{\deg}, Josephson coupling is suppressed, and
eventually disappears at 45{\deg}. The observed twist angle dependence of the
Josephson coupling can be explained quantitatively by theoretical calculation
with the d-wave superconducting order parameter of Bi-2212 and finite tunneling
incoherence of the junction. Our results revealed the anisotropic nature of
Bi-2212 and provided a novel fabrication technique for vdW-based twistronics
platforms compatible with air-sensitive vdW materials.
