Lessons learned from dinuclear lanthanide nano-magnets

Abstract

The quest for higher density information storage has led to the investigation of Single-Molecule Magnets (SMMs) as potential molecules to be applied in materials such as hard discs. In order for this to occur, one must first design metal complexes which can retain magnetic information at temperatures where these applications become possible. This can only be achieved through answering and understanding fundamental questions regarding the observed physical properties of SMMs. While mononuclear lanthanide complexes have shown promise in obtaining high energy barriers for the reversal of the magnetisation they are limited to Single-Ion Magnet behaviour intrinsic to one metal centre with a limited number of unpaired electrons. As a way of increasing the effective anisotropic barrier, systems with higher nuclearity have been sought to increase the spin ground state of the molecule. Dinuclear complexes are presented as key compounds in studying and understanding the nature of magnetic interactions between metal ions. This tutorial review will span a number of dinuclear 4f complexes which have been critical in our understanding of the way in which lanthanide centres in a complex interact magnetically. It will examine key bridging moieties from the more common oxygen-based groups to newly discovered radical-based bridges and draw conclusions regarding the most effective superexchange pathways allowing the most efficient intracomplex interactions.

Modulating the Slow Relaxation Dynamics of Binuclear Dysprosium(III) Complexes through Coordination Geometry

“…As the overall electronic structure of a Dy III ion is very sensitive to its coordination environment, minor changes in the ligand systems can significantly affect the magnetic properties of the complexes [15][16][17]. Most of the reports on Ln-based SMMs concentrated mainly on either changing the Ln ion keeping the ligand system constant [18][19][20] or changing the ligand but keeping the coordination environment around the Ln ion unchanged [8]. Only few studies are known where modification in the ligand system was done to tune the relaxation behavior in the complexes [21][22][23][24][25][26].…”

“…The importance of SMMs is that, even in the absence of an external magnetic field, they can preserve the magnetization for long period of time at low temperatures. After an extensive research on 3d metal complexes in the last decade [2][3][4], a rapid development of Ln based SMMs has been observed in recent years [5][6][7][8][9]. Compared to 3d metals, Ln based SMMs are mostly investigated owing to the fact that the Ln III ions such as Dy III , Tb III , Er III , and Ho III have huge and unquenched orbital angular momentum [10][11][12] which causes substantial magnetic anisotropy.…”

Using the Singly Deprotonated Triethanolamine to Prepare Dinuclear Lanthanide(III) Complexes: Synthesis, Structural Characterization and Magnetic Studies

“…More importantly, dinuclear Ln III SMMs are very important model systems to answer basic questions regarding single-ion relaxation vs. slow magnetic relaxation arising from the molecule as an entity. Thus, Ln III 2 complexes are highly desirable [10][11][12][13][14][15][16][17][18][19][20]. Another interesting area to which dinuclear lanthanide(III) complexes (and also mononuclear ones) are relevant is quantum computation; Ln III ions are promising candidates for encoding quantum information [21,22].…”

“…Dinuclear complexes represent the simplest molecular entities which allow the study of magnetic interactions between Ln III spin carriers [10]. By studying such systems, researchers could expect to understand the nature and strength of Ln III ··· Ln III exchange interactions, as well as possible alignment of spin vectors and anisotropy axes.…”

Systematic studies of hexanuclear {MIII4LnIII2} complexes (M = Fe, Ga; Ln = Er, Ho): structures, magnetic properties and SMM behavior

“…Due to the large unquenched orbital angular momentum, Ln III ions can exhibit large single-ion magnetic anisotropies, leading to significant energy barriers in lanthanide-based SMMs. [2][3][4] Therefore, the synthesis and characterization of high-nuclearity 3d-4f SMMs have attracted intensive attention in recent years. [5][6][7][8][9] Although many studies on 4f-4f or 3d-3d interactions have been reported, [10][11][12][13][14][15][16][17] research on 3d-4f exchange interactions is less developed.…”