Bonding and Suppression of a Magnetic Phase Transition in EuMnP.

Electrons in solids often adopt complex patterns of chemical bonding driven by the competition between energy gains from covalency and delocalization, and energy costs of double occupation to satisfy Pauli exclusion, with multiple intermediate states in the transition between highly localized, and magnetic, and delocalized, and nonmagnetic limits. Herein, we report a chemical pressure-driven transition from a proper Mn magnetic ordering phase transition to a Mn magnetic phase crossover in EuMnP the limiting end member of the EuMnX (X = Sb, As, P) family of layered materials. This loss of a magnetic ordering occurs despite EuMnP remaining an insulator at all temperatures, and with a phase transition to long-range Eu antiferromagnetic order at ≈ 17 K.