Weak ferromagnetism with very large canting in a chiral lattice: (pyrimidine)2FeCl2

TL;DR

This study reports a chiral lattice compound, (pyrimidine)2FeCl2, exhibiting a rare large canting of magnetic moments leading to weak ferromagnetism, with detailed analysis of its magnetic structure and implications for chiral magnetic materials.

Contribution

It reveals a new chiral compound with an exceptionally large magnetic canting and weak ferromagnetism, advancing understanding of chiral magnetic interactions in coordination compounds.

Findings

Large magnetic canting of 14 degrees observed

Weak ferromagnetism with 1 μ_B component identified

Magnetic structure is non-chiral despite chiral lattice

Abstract

The transition metal coordination compound (pyrimidine)2FeCl2 crystallizes in a chiral lattice, space group I 4_1 2 2 (or I4_3 2 2). Combined magnetization, Mossbauer spectroscopy and powder neutron diffraction studies reveal that it is a canted antiferromagnet below T_N = 6.4 K with an unusually large canting of the magnetic moments of 14 deg. from their general antiferromagnetic alignment, one of the largest reported to date. This results in weak ferromagnetism with a ferromagnetic component of 1 mu_B. The large canting is due to the interplay between the antiferromagnetic exchange interaction and the local single-ion anisotropy in the chiral lattice. The magnetically ordered structure of (pyrimidine)2FeCl2, however, is not chiral. The implications of these findings for the search of molecule based materials exhibiting chiral magnetic ordering is discussed.