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Long decoherence time is a key consideration for molecular magnets in the application of the quantum computation. Although previous studies have shown that the local symmetry of spin carriers plays a crucial part in the spin-lattice relaxation process, its role in the spin decoherence is still unclear. Herein, two nine-coordinated capped square ant...
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Qubits are the basic unit of quantum information and computation. To realize quantum computing and information processing, the decoherence times of qubits must be long enough. Among the studies of molecule‐based electron spin qubits, most of the work focused on the ions with the spin S=1/2, where only single‐bit gates can be constructed. However, q...
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... 6 One of the key issues is to better understand the mechanism of T 1 and T 2 in the spin relaxation of magnetic systems. This may take place due to the internal nuclear spin fluctuations, 7 the spin flip-flop processes, [8][9][10][11] molecular symmetry, 12 spinphonon coupling, [13][14][15][16][17] and so forth. Among them, the first three are fully studied, but the connotation of spinphonon coupling is not clear enough as of now. ...
... kOe (Figure 2c). According to our references, 12,31 in the spin-phonon-bottleneck-dominated relaxation process, the relaxation time, τ, is proportional to the crystal size. Hence, the variable-frequency ac magnetic susceptibility of ground samples was measured at 2 K with a different external dc field in the same way (Supporting Information Figure S4). ...
... The parameter n is closed to 3, which is consistent with a system with a strong spin-phonon bottleneck. 12,14,27,30,32,33 When fitting the fast process (area B in Figure 2a) of 1-H at 0.6 kOe, a QTM process should be considered because of the short temperature-independent relaxation times at low temperatures. This phenomenon would stem from the energy overlap between the unpaired electron and the low-energy barrier vibrations 18,21,33 or the methyl tunneling rotations 34 at the given magnetic field. ...
Nd-based nitride clusterfullerenes NdM2N@C80 with rare-earth metals of different sizes (M = Sc, Y, Lu) were synthesized to elucidate the influence of the cluster composition, shape and internal strain on the structural and magnetic properties. Single crystal X-ray diffraction revealed a very short Nd-N bond length in NdSc2N@C80. For Lu and Y analogs, the further shortening of the Nd-N bond and pyramidalization of the NdM2N cluster is predicted by DFT calculations as a result of the increased cluster size and a strain caused by the limited size of the fullerene cage. The short distance between Nd and nitride ion lead to a very large ligand-field splitting of Nd3+ of 1100-1200 cm−1 , while the variation of the NdM2N cluster composition and concomitant internal strain result in the noticeable modulation of the splitting, which could be directly assessed from the well-resolved fine structure in Nd-based photoluminescence spectra of NdM2N@C80 clusterfullerenes. Photoluminescence measurements also revealed an unprecedentedly strong nephelauxetic effect, pointing to the high degree of covalency. The latter appears detrimental to the magnetic axiality despite the strong ligand field. As a result, the ground magnetic state has considerable transversal components of the pseudospin g-tensor, and the slow magnetic relaxation of NdSc2N@C80 could be observed by AC magnetometry only in the presence of a magnetic field. A combination of the well-resolved magneto-optical states and slow relaxation of magnetization suggests that Nd clusterfullerenes can be useful building blocks for magneto-photonic quantum technologies.
Spin, the intrinsic angular momentum of an electron, is increasingly being recognized as a versatile tool in the development of next-generation technologies, including quantum computing, sensing, and communication, which exploit quantum phenomena. The burgeoning theoretical understanding coupled with technological advancements have catalyzed research efforts aimed at controlling and manipulating the optical, electrical, magnetic, and thermal properties of materials through the modulation of spin states. Among the myriad of techniques available for investigating these spin-dependent properties, Electron Spin Resonance (ESR), sometimes referred to as electron paramagnetic resonance, stands out as one of the most direct and potent methods to probe electron spin dynamics irrespective of the material environment. ESR furnishes insightful data on the states of individual spins and clusters, spin coherence via relaxation time measurements, and inter-spin distances from spin–spin interaction measurements. Additionally, ESR facilitates the manipulation of spin systems by tailoring the Zeeman energy through the modulation of the external magnetic field, and critically, by the remote manipulation of spins via the application of microwave pulses at resonance frequencies. Modern ESR experimental setups are versatile and can be employed across a wide temperature spectrum—from a few Kelvin, where quantum effects are pronounced, to room temperature and beyond. This adaptability enhances the utility of ESR in investigating the spin-dependent properties in condensed matter systems. Notwithstanding the tremendous potential and advantages that ESR offers, it remains underutilized, especially when compared to inelastic neutron scattering (INS) and nuclear magnetic resonance, despite the latter being more expensive and INS being less accessible. In this review, we elucidate the fundamental principles of ESR, with an emphasis on magnetic and spin interactions in solids, and explore the potential of ESR in advancing the understanding of spin properties across a diverse array of materials science disciplines. We commence with a concise introduction to spin-related physics, followed by the application of ESR in characterizing spin systems. As such, this review aims to serve as a valuable resource for a broad audience, ranging from novices to experts, who are keen on unraveling spin phenomena and dynamics in materials science and condensed matter physics.
Polymorphic layered lanthanide coordination polymers provide opportunities to study the effect of intralayer and interlayer interactions on their magnetic dynamics. Herein we report a series of layered lanthanide phosphonates, namely, α-Ln(2-qpH)(SO4)(H2O)2 (Ln = Sm) (α-Ln), β-Ln(2-qpH)(SO4)(H2O)2 (Ln = Pr, Nd, Sm) (β-Ln) and γ-Ln(2-qpH)(SO4)(H2O)2 (Ln = La, Ce, Pr, Nd, Sm) (γ-Ln) (2-qpH2 = 2-quinolinephosphonic acid), which crystallize in monoclinic P21/c (α-Ln), triclinic P1̄ (β-Ln) and orthorhombic Pbca (γ-Ln) space groups, respectively. The structural differences between the β- and γ-phases lie not only in the intralayer but also in the interlayer. Within the layers, the Ln2O2 dimers are aligned parallel in the β-phase, but are non-parallel in the γ-phase. In the interlayer, there are π-π interactions between the quinoline groups in the α- and β-phases but not in the γ-phase. Magnetic studies reveal a field-induced slow relaxation of the magnetisation at low temperatures for compounds γ-Ce, β-Nd, and γ-Nd, and the impact of polymorphism on the magnetic dynamics of Nd(III) compounds is discussed.
Single-ion magnets (SIMs) have attracted wide attention in recent years. Despite tremendous progress in late lanthanide SIMs, reports on early lanthanides exhibiting SIM characteristics are scarce. A series of five novel 18-crown-6 encapsulated mononuclear early lanthanide(III) organophosphates, [{(18-crown-6)Ln(dippH)3}{(18-crown-6)Ln(dippH)2(dippH2)}]·[I3] [Ln = Ce (1), Pr (2), Nd (3)] and [{Ln(18-crown-6)(dippH)2(H2O)}·{I3}] [Ln = Sm (4) and Eu (5)], have been synthesised in the present study. 18-crown-6 coordinates to Ln(III) ions in an equatorial position while the axial positions are occupied by either three phosphate moieties as in 1-3 or two phosphate moieties and one water molecule as in 4 and 5, resulting in a muffin-shaped coordination geometry around the Ln(III) centres. Magnetic susceptibility measurements reveal that Ce and Nd complexes are field-induced single-ion magnets with significant barrier heights. Furthermore, the ab initio CASSCF/RASSI-SO/SINGLE_ANISO calculations on complexes 1 and 3 reveal significant QTM in the ground state rationalising the field-induced single-ion magnetism behaviour of these complexes.
The elaborate collocation of the layered structure employed the sodium dysprosium 1-naphthylphosphonate and the flexible monopyrazinyl hydrazone molecular tool acted (E)-N'-(2-hydroxy-3-methoxybenzylidene)pyrazine-2-carbohydrazide results in the formation of a cutted heterometallic hendecanuclear...
This paper reports a quasilinear hydrazone-based mononuclear dysprosium(III) compound, namely, {Dy(Hppyh)2(SCN)3} 2MeOH (I), where Hppyh is Pyrazine-2-carboxylic acid pyridin-2-ylmethylene-hydrazide. Compound I behaves as a single-ion magnet (SIM) behavior based on...
This paper reports two closely related heteropentanuclear manganese complexes, namely, {Na2Mn3(opch)3(μ4-O)(μ2-N3) (μ2-AcO)(μ2-MeO)}·6CH3OH·0.5H2O (1) and {Na2Mn3(opch)3(μ4-O)(μ2-N3)2(μ2-AcO)}·2.5CH3OH·2H2O (2), where H2opch is (E)-N'-(2-hydroxy-3-methoxybenzylidene)pyrazine-2-carbohydrazide. Single-crystal X-ray diffraction analysis reveals that the trigonal bipyramidal skeletons in both complexes are comparable, where a perfect triangular Mn3 motif occupies the equatorial plane. Magnetic investigations suggest that overall antiferromagnetic coupling is present within the triangles of 1 and 2. However, their dynamic magnetic properties are drastically distinct. Indeed, complexes 1 and 2 show two kinds of dual slow magnetic relaxation processes that correspond to anisotropy barriers (Δ) of 9.2 cm-1 (11.4 cm-1 for 2) and 12.8 cm-1 (30.0 cm-1 for 2) for the low- and high-frequency domains, respectively. More importantly, a further comparative study of the structure and magnetism indicates that the coordination sphere of these two model complexes with the homologous hydrazone-based coordination sites undergoes an alteration from methoxide-O to azide-N upon a subtle change of the auxiliary anion accompanied by modulating octahedron geometries, leading to a further influence on different relaxation dynamics.
Magnetic double deflection experiments reveal that nuclear spins diminish electron spin coherence in isolated AlSn12 clusters. A temperature-dependent fraction of the endohedral cage clusters show superatomic response in Stern-Gerlach experiments which allows one to detect spin flips under controlled conditions in a double deflection arrangement. The concentration of nuclear spins in the tin cage is varied by using isotopically enriched tin samples. Hyperfine interaction, nuclear spin statistics and spin dynamics are discussed in detail. It is demonstrated that state-interference in the multistate Landau-Zener system AlSn12 explains why the spin decoherence is significantly increased when one or two nuclear spins are already present in the cluster, while the spin coherence no longer changes significantly with the addition of further nuclear spins.
