Rotating Magnetocaloric Effect in an Anisotropic Molecular Dimer

Abstract

In contrast to the mainstream research on molecular refrigerants that seeks magnetically isotropic molecules, we show that the magnetic anisotropy of dysprosium acetate tetrahydrate, [{Dy(OAc)3(H2O)2}2]⋅4 H2O (1), can be efficiently used for cooling below liquid‐helium temperature. This is attained by rotating aligned single‐crystal samples in a constant applied magnetic field. The envisioned advantages are fast cooling cycles and potentially compact refrigerators.

Verdazyl Radical, a Building Block for a Six-Spin-Center 2p–3d–4f Single-Molecule Magnet

“…The central core of the cluster is a {Dy 2 ac 4 } unit. The two dysprosium(III) ions are connected by two (η 2 :η 1 :μ 2 )-acetato-κ 3 O,O′:O′ already present in the initial [Dy 2 ac 6 (H 2 O) 4 ]•4H 2 O 17,18 and two additional (η 1 :η 1 :μ 2 )-acetato-κ 2 O,O′:O′ . This Dy 2 core is thus reminiscent of the paddle-wheel motif well-known for TM ions.…”

“…Nonetheless, at this point, the origins of the SMM properties remain elusive. In turn, no SMM properties are observed in the dysprosium(III) acetate itself, 17,18 whereas the slow relaxation of magnetization observed in (vdpyCH 2 O) 2 Co 2 Dy 2 ac 8 is reminiscent of the phenomena recently observed in antiferromagnetically coupled Dy 2 Ga 4 clusters. 37 Modification of the acetate bridges as well as the magnetic influence of the 2p and 3d paramagnetic partners of the cluster might be at the origin of the observed properties.…”

Self-Enhancement of Rotating Magnetocaloric Effect in Anisotropic Two-Dimensional (2D) Cyanido-Bridged MnII–NbIV Molecular Ferrimagnet

“…However, this limits the maximum field, which can be employed for this type of cooling below 2.0 T. The RMCE is a very fresh topic and the number of relevant reports is limited, which mainly concern inorganic materials. 36−41 To the best of our knowledge, there has been only one work about the molecular compound: 43 It is an anisotropic molecular dimer and a paramagnet with a sizable RMCE in the cryogenic temperature range.…”

Get under the Umbrella: A Comprehensive Gateway for Researchers on Lanthanide‐Based Single‐Molecule Magnets

“…Then, the field develop quickly with the observation of quantum signatures in direct MCE measurement in 2014 [69] or the demonstration of Rotating Magnetocaloric Effect (RMCE) on dimeric Dy‐SMM by M. Evangelisti et al. in 2016 [70] …”