Tutorial: a beginner’s guide to interpreting magnetic susceptibility data with the Curie-Weiss law

Abstract

Magnetic susceptibility measurements are often the first characterization tool that researchers turn to when beginning to assess the magnetic nature of a newly discovered material. Breakthroughs in instrumentation have made the collection of high quality magnetic susceptibility data more accessible than ever before. However, the analysis of susceptibility data remains a common challenge for newcomers to the field of magnetism. While a comprehensive treatment of the theoretical aspects of magnetism are found in numerous excellent textbooks, there is a gap at the point of practical application. We were inspired by this obstacle to put together this guide to the analysis and interpretation of magnetic susceptibility data, with an emphasis on materials that exhibit Curie-Weiss paramagnetism.

A mixed-valence copper chloride coordination polymer composed of one-dimensional cationic and anionic substructures

“…The slope (1/ C ) is the inverse of the Curie constant, and is used to calculate the effective magnetic moment ( μ eff ) in the units of Bohr magneton ( μ B ). 46 The calculated value of the effective moment is 2.04 μ B , which is slightly larger than the theoretical spin-only value (1.73 μ B ) for the Cu II ion (d 9 , S = 1/2). This slight deviation is mainly due to the contribution of spin–orbit coupling, which is often neglected in insulating 3d transition metal compounds.…”

Assembling diuranium complexes in different states of charge with a bridging redox-active ligand

“…The χ versus T plots for 2, 3 and 4 show a continuous increase towards low temperatures, characteristic of magnetically isolated uranium centers, but the presence of weak magnetic coupling cannot be ruled out. 21 The magnetic susceptibility curve of 1 also shows a continuous increase but starts to plateau around 12 K until rapidly rising below 5 K (Fig. S27 † ), possibly hinting at a weak magnetic interaction between the uranium centers, which is obscured by a paramagnetic impurity.…”

Slow magnetic relaxation in Fe(ii)m-terphenyl complexes

“…Initially, a global fitting of both the susceptibility and magnetisation was attempted for 1–5 . 62 To avoid over-parameterisation, the CASSCF-SO values were used as a starting point, with g x = g y ≠ g z and B 2 2 fixed to the CASSCF-SO value (see above and Table S6†). However, the obtained fit was biased towards the magnetisation curves, which drastically worsened the model's agreement with the susceptibility traces.…”

“…As such, the magnetic data can be modelled through a combination of a crystal field and a Zeeman Hamiltonian (equation 2), 58 as implemented in PHI: 61 (2) Initially, a global fitting of both the susceptibility and magnetisation was attempted for 1-5. 62 To avoid over-parameterisation, the CASSCF-SO values were used as a starting point, with and…”