This note extends the construction of D k D₊ ALF gravitational instantons in Schroers–Singer Q. J. Math. 72 (2021), pp. 277–337 to a new case where the non-linear superposition is given by the D 1 D₁ Atiyah–Hitchin metric and k − 1 k-1 copies of A 0 A₀ Taub-NUT metrics. We then give a general class of ALF spaces such that each of them contains a non-holomorphic minimal sphere. Together with Foscolo’s construction J. Differential Geom. 112 (2019), pp. 79–120 this gives a large class of K 3 K3 surfaces containing non-holomorphic minimal spheres.
Xuwen Zhu (Tue,) studied this question.