An NCN-pincer ligand dysprosium single-ion magnet showing magnetic relaxation via the second excited state

Abstract

Single-molecule magnets are compounds that exhibit magnetic bistability purely of molecular origin. The control of anisotropy and suppression of quantum tunneling to obtain a comprehensive picture of the relaxation pathway manifold, is of utmost importance with the ultimate goal of slowing the relaxation dynamics within single-molecule magnets to facilitate their potential applications. Combined ab initio calculations and detailed magnetization dynamics studies reveal the unprecedented relaxation mediated via the second excited state within a new DyNCN system comprising a valence-localized carbon coordinated to a single dysprosium(III) ion. The essentially C2v symmetry of the DyIII ion results in a new relaxation mechanism, hitherto unknown for mononuclear DyIII complexes, opening new perspectives for means of enhancing the anisotropy contribution to the spin-relaxation barrier.

Molecular single-ion magnets based on lanthanides and actinides: Design considerations and new advances in the context of quantum technologies

“…Single-ion magnets (SIMs) are simply a subclass of SMMs wherein the electronic spin term originates from a single magnetic centre [7,8]. In SIMs, the ion bearing the spin is most commonly a transition metal [9][10][11][12][13], lanthanoid [14][15][16][17][18][19][20][21][22], or actinoid [23][24][25][26][27][28][29][30]. The term SIM is somewhat of a misnomer: all SIMs are molecular in nature since the ligand field is a vital prerequisite for their slow relaxation.…”

A Basis for Lanthanide Single-Molecule Magnets

“…Here, the bistability is derived from the large magnetic ground state (S) and negative anisotropy (D) of Mn 12 molecule, which leads to the slow relaxation of magnetization, analogous to that used for superparamagnets, as a result of overcoming the anisotropy barrier (ΔE). Subsequently, this area of chemistry has experienced an almost unparalleled growth, as evidenced by not only the sheer number of SMMs reported with 3d (Mn [24][25][26][27], Fe [28,29], Co [30] et al), 4d (Mo) [31], 5d (Re) [32,33], 4f (Dy [2,6,34,35], Tb [14,36], Er [15,37] et al), and 5f (U [38], Np [39]) ions but also the ever-expanding scope of the research [40]. Herein, two parameters, U eff and T B , are very critical to measure the success (or not) of an SMM.…”

“…Further studies for redox, heteroleptic, and multidecker species of this class of complexes [53][54][55][56][57] were performed and thus created a high effective barrier record of SMM field, U eff = 652 cm −1 (938 K) [56], which surpasses by an order of magnitude that obtained for the original Mn 12 SMM. Remarkably, the interest in new kinds of mononuclear lanthanide SMMs [58] is continuing in recent years, and some of them show the very high effective barrier and blocking temperature, such as β-diketone [59][60][61][62], organometallic [35,37,44,63], 2013 [74] and some low-symmetry [20,64] lanthanide systems (Table 1.4). As such, the mononuclear SMMs are called single-ion magnets (SIMs) in some recent papers.…”

Field-induced single-ion magnetic behaviour in a highly luminescent Er3+ complex

“…Such materials have an increased value: they may provide a correlation between photoluminescence, static susceptibilities and dynamic magnetic relaxation. The measurement of the energy gap between the ground and excited states by two independent techniques may reveal if the magnetisation reversal is achieved through the first excited state or through higher excited states, a hypothesis only recently raised [19,20].…”