Certain results on a type of contact metric manifold

Abstract

Let \(M\) be a \(3\)-dimensional almost contact metric manifold satisfying \((*)\) condition. We denote such a manifold by \(M^{*}\). At first we study symmetric and skew-symmetric parallel tensor of type \((0,2)\) in \(M^{*}\). Next we prove that a non-cosymplectic manifold \(M^{*}\) is Ricci semisymmetric if and only if it is Einstein. Also we study locally \(\phi \)-symmetry and \(\eta \)-parallel Ricci tensor of \(M^{*}\). Finally, we prove that if a non-cosymplectic \(M^{*}\) is Einstein, then the manifold is Sasakian.