Magnetische Suszeptibilitätsmessung und ⁵⁷Fe‐Mößbauer‐ Spektroskopie an einem ferromagnetischen Fe^III₄Dy₄‐Ring

Abstract

In memoriam Ian J. HewittBei der Suche nach kleineren und effektiveren magnetischen Materialien hat sich die Aufmerksamkeit in letzter Zeit auf Fe III -4f-Heterometallkomplexe gerichtet. Diese Komplexe kombinieren paramagnetische High-spin-Fe III -Ionen mit stark anisotropen 4f-Ionen, und einige dieser Komplexe sind Einzelmolekülmagnete (SMMs).[1] In den meisten der bisher beschriebenen SMMs ist die dominierende magnetische Wechselwirkung von antiferromagnetischer Natur, aber es besteht wenig Zweifel daran, dass das Design von neuartigen ferromagnetischen molekularen Materialien mit dem Ziel, molekulare Systeme mit einem großen Spin herzustellen, [2] von äußerstem Interesse ist. [3,4]

Pentanuclear Spirocyclic Ni4Ln Derivatives: Field Induced Slow Magnetic Relaxation in the Dysprosium and Erbium Analogues

“…Heterometallic complexes containing 3d and 4f block paramagnetic ions have been extensively considered since the revolutionary investigation by Gatteschi et al on the Cu II /Gd III based complexes which bestowed a whim to the advancement of 3d–4f associated chemistry . Until now, numerous 3d‐4f heterometallic molecular magnetic assembly with diverse structures and topologies of paramagnetic centres have been revealed based on cobalt(II), copper(II), chromium(III), manganese (II/III),, iron(II/III) ion. The appraisal of literature study revealed that ferromagnetic coupling, that is favourable for slaking of the QTM phenomena and improving energy barriers, amongst Cu II /Ln III[27,28] and Ni II /Ln III[29–34] ions indicate an advantageous combination to assemble 3d–4f heterometallic complexes with novel topologies for SMM study.…”

Coexistence of Distinct Single‐Ion and Exchange‐Based Mechanisms for Blocking of Magnetization in a CoII2DyIII2 Single‐Molecule Magnet

“…To confirm the SMM behavior, hysteresis loops were recorded using a micro‐Hall magnetometer for which a sufficient range of sweep rates is available11 on a crystal well coated in Apiezon grease. Even if such a crystal fractures on cooling the grease prevents any movement of the fragments and the measurements correspond to those on aligned single crystallites.…”

Differentiation of Highly Anisotropic TbIII and DyIII with 57Fe Mössbauer Spectroscopy

“… The cores of Fe‐Ln compounds discussed herein: Fe 3 Ln (top),6a Fe 4 Ln 4 (middle),6b and Fe 2 Ln 2 (bottom) 5…”

“…Other examples analyzed herein are two octanuclear complexes [Fe III 4 (Tb/Dy) 4 (teaH) 8 (N 3 ) 8 (H 2 O)] (teaH=triethanolamine), denoted Fe 4 Ln 4 6b. The structure of these two isostructural compounds is based on a ring‐like {Fe 4 Ln 4 } 24+ core with alternating Fe III and Ln III centers.…”