Let $K$ be a covariance matrix. It is positive semidefinite, its diagonal elements are all 1, and its off-diagonals are between -1 and 1. Let $K.^2$ be its element-wise power (Hadamard power). Can we show that maximum eigenvalue of $K$ are great or equal than the maximum eigenvalue of $K.^2$?

$\begingroup$
$\endgroup$

Theorem 3 provides a stronger result. Take A=B=K and specialize to k=1 in the majorization.