Magnetic Behavior of Single-Chain Magnets in Metal Organic Frameworks CPO-27-Co

Abstract

Nanoscale molecular magnets of highly porous and crystalline Metal-organic frameworks (MOFs) have attracted increasing interest in recent years because of their potential application in nano-magnetic device or matrices for encapsulating of a large variety of substances. For that, a fundamental understanding of its origin of magnetism in MOFs would be essential and will provide useful insight for intelligent design of their electromagnetic properties (e.g., single-chain magnets, single-ion magnets or single-molecule magnets). Herein, we experimentally investigate the magnetic property of hexagonal 1-D channel MOFs composed of metal(cobalt) cluster connected with organic linker (so-called CPO-27-Co). Through a fundamental physisorption analysis, in-depth magnetic studies by use of superconducting quantum interference device (SQUID) magnetometry, and theoretically by the application of an isotropic Heisenberg Hamiltonian, we found a magnetic configuration of CPO-27-Co exhibiting both a weak ferro-and antiferromagnetism with cobalt magne-tocrystalline anisotropy. Interestingly, when a magnetic configuration of cobalt cluster (instead of ionic cobalt inside cluster of CPO-27) are considered, the inter Co cluster interaction exhibits superparamagnetic behavior while inside of Co cluster (ionic Co-Co interaction) is dominated by a weak ferromagnetic component.