A {Cr^III₂Dy^III₂} Single‐Molecule Magnet: Enhancing the Blocking Temperature through 3d Magnetic Exchange

Abstract

Schmetterlingsmagnet: Der Austausch eines diamagnetischen CoIII gegen CrIII in einem 3d‐4f‐Schmetterlingskomplex führt zu deutlich verbesserten Eigenschaften als Einzelmolekülmagnet. Längere Relaxationszeiten mit Hysterese werden beobachtet, was auf die Austauschwechselwirkung zwischen den DyIII‐ und CrIII‐Ionen zurückzuführen ist, die in einer mehrstufigen Austauschbarriere mit reduziertem Quantentunneln resultiert.

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

“…This happens to be the major challenge in designing high‐performance SMM. According to recent studies, the two significant approaches employed for subduing QTM are i) construction of crystal‐field environment having an axial symmetry around the Ln III ions ii) to create effective exchange coupling among the metal ions . It was noted that for 3d/4f complexes magnetic exchange interaction are stronger than the 4f complexes .…”

Magnetic Nature of the CrIII–LnIII Interactions in [CrIII2LnIII3] Clusters with Slow Magnetic Relaxation

“…On the other hand, much work has concentrated on mixing 4 f ions with anisotropic 3 d ions to prepare the former 3 d ‐based SMMs; however, some isotropic ions can also be favorable in 3 d –4 f coordination clusters with enhanced SMM properties . Since the [Cr III 4 Dy III 4 ] SMM was reported, 3 d –4 f SMMs containing Cr III ions have drawn great attention . More recently, a rare [Cr III 2 Dy III 2 ] SMM with a high U eff of 77 K and large coercive magnetic fields was synthesized, which can significantly reduce the quantum tunneling of magnetization (QTM) due to the exchange interaction between Cr III and Dy III ions .…”

“…Since the [Cr III 4 Dy III 4 ] SMM was reported, 3 d –4 f SMMs containing Cr III ions have drawn great attention . More recently, a rare [Cr III 2 Dy III 2 ] SMM with a high U eff of 77 K and large coercive magnetic fields was synthesized, which can significantly reduce the quantum tunneling of magnetization (QTM) due to the exchange interaction between Cr III and Dy III ions . Following work showed that the U eff was related to the magnitude of exchange between magnetic centers by comparing it to two families of Cr III ‐containing SMMs .…”

Single‐Molecule Magnet and Magnetothermal Properties of Two‐Dimensional Polymers Containing Heterometallic [Cu5Ln2] (Ln = GdIII and DyIII) Motifs

“…Moreover, the random transversal field for the Dy III ions created by the weakly exchange‐coupled Cu II metal ion also favors the faster zero‐field QTM process. In this respect, it should be noted that when the 3d–4f magnetic exchange coupling is strong enough, the exchange‐coupled levels are well separated and the QTM is suppressed, so that large energy barriers, hysteresis loops, and relaxation times are observed …”