Magnetic properties of alpha-iron(II) phthalocyanine

TL;DR

This study investigates the magnetic behavior of alpha-iron(II) phthalocyanine, revealing ferromagnetic chain coupling, weak interchain interactions, and complex low-temperature magnetic phenomena influenced by defects and impurities.

Contribution

It provides detailed experimental insights into the magnetic coupling and low-temperature behavior of alpha-iron(II) phthalocyanine, highlighting the effects of defects on magnetic ordering.

Findings

Iron atoms form ferromagnetic Ising chains

Weak antiferromagnetic interchain coupling observed

Disordered 3D magnetic state below 10 K

Abstract

We report on the magnetic properties of the supra-molecular compound iron(II) phthalocyanine in its alpha-form. dc- and ac-susceptometry measurements and Mossbauer experiments show that the iron atoms are strongly magnetically coupled into ferromagnetic Ising chains with very weak antiferromagnetic interchain coupling. The transition to 3D magnetic ordering below 10 K is hindered by the presence of impurities or other defects, by which the domain-wall arrangements along individual chains become gradually blocked/frozen, leading to a disordered 3D distribution of ferromagnetic chain segments. Below 5 K, field-cooled and zero-field-cooled magnetization measurements show strong irreversible behavior, attributed to pinning of the domain-walls by the randomly distributed defects in combination with the interchain coupling. High-field magnetization experiments reveal a canted arrangement of the moments in adjacent ferromagnetic chains.