Pressure Dependence of the Magnetization of M^II (N(CN)₂)2: Mechanism for the Long Range Magnetic Ordering

Abstract

The ac-susceptibilities of the isostructural metal-orgnets magnets, M^II(N(CN)²)² (M = Ni (1), Co (2) and Fe (3)) have been studied as a function of temperature and pressure. Large variation in behaviors has been observed: the transition temperature initially increases in all three compounds and at higher pressures that for (1) saturates, for (2) decreases and for (3) increases continuously. These behaviors are due to the competition between antiferromagnetic (t^2g ↔e^g) and ferromagnetic (t^2g ↔ t^2g and e^g ↔ e^g) inteeractions to the most dominant exchange pathway, M—N≡C-N—M. A mechanism for the magnetic ordering is proposed.

Key Words:

• Cobalt
• Dicyanamide
• Iron
• Magnetism
• Nickel
• Pressure