We report a family of organometallic rare-earth complexes with the general formula (COT)M(Cp) (where (COT) = cyclooctatetraenide, (Cp) = 1,2,4-tri(-butyl)cyclopentadienide, M = Y(iii), Nd(iii), Dy(iii) and Er(iii)). Similarly to the prototypical Er(iii) analog featuring pentamethylcyclopentadienyl ligand (Cp*), (COT)Er(Cp) behaves as a single-ion magnet. However, the introduction of the sterically demanding (Cp) imposes geometric constraints that lead to a simplified magnetic relaxation behavior compared to the (Cp*) containing complexes. Consequently, (COT)Er(Cp) can be viewed as a model representative of this organometallic single-ion magnet architecture. In addition, we demonstrate that the increased steric profile associated with the (Cp) ligand permits preparation, structural characterization and interrogation of magnetic properties of the early-lanthanide complex, (COT)Nd(Cp). Such a mononuclear derivative could not be obtained when a (Cp*) ligand was employed, a testament to larger ionic radius of this early lanthanide ion.
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http://dx.doi.org/10.1039/d2sc02560d | DOI Listing |
J Phys Condens Matter
January 2025
Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, No.8 South Third Street, Zhongguancun, Beijing, 100190, CHINA.
We systematically investigate the magnetization and thermodynamic responses associated with antiferromagnetic (AFM) transitions in single crystals of the magnetic semiconductor Eu3InAs3. The linear thermal expansion measurements around the AFM transition temperatures, TN1 and TN2, indicate an expansion along the a axis and contraction along the b and c axes. The calculated ∆V/V(T) shows a continuous change at TN, indicating a second-order magnetic phase transition.
View Article and Find Full Text PDFJ Phys Condens Matter
January 2025
Northeastern University, College of Science, Northeastern University, Shenyang 110819, China, Shenyang, Liaoning, 110819, CHINA.
Based on the recent discovery of intrinsic magnetism in monolayer films VSe2, we have constructed a two-dimensional (2D) Heisenberg model incorporating the 1T and 2H structures. These configurations consist of three layers: the upper and lower surface layers and a middle layer. Using the retarded Green's function method, we investigate the spin-wave energy spectrum, spin-wave density of states, and transition temperature of the system.
View Article and Find Full Text PDFJ Phys Condens Matter
January 2025
Department of Physics, Danmarks Tekniske Universitet, Department of Physics, Technical University of Denmark, Kgs Lyngby, 2800, DENMARK.
The magnetic properties of solids are typically analyzed in terms of Heisenberg models where the electronic structure is approximated by interacting localized spins. However, even in such models the evaluation of thermodynamic properties constitutes a major challenge and is usually handled by a mean field decoupling scheme. The random phase approximation (RPA) comprises a common approach and is often applied to evaluate critical temperatures although it is well known that the method is only accurate well below the critical temperature.
View Article and Find Full Text PDFIsostructural Dy(III) and Er(III) complexes [L12Ln(H2O)5][I]3·L12·(CH2Cl2) (Ln = Dy (1), Er (3)) and [L22Ln(H2O)5][I]3·L22·(CH2Cl2)2 (Ln = Dy (2), Er (4)), with distorted pentagonal bipyramidal geometry (D5h) around the central metal were synthesized by utilizing two bulky phosphonamide ligands, adamantyl phosphonamide, (Ad)P(O)(NHiPr)2 (L1) and carbazolyl phosphoramide (Cz)P(O)(NHiPr)2 (L2). The resultant complexes were investigated for their magnetic properties in order to elucidate the impact of modification of the coordinating P-O bond environment either by increasing steric bulk and/or introduction of a third P-N bond at the central phosphorus atom. Magnetic studies revealed substantial energy barriers (Ueff) of 640 K and 560 K for Dy compounds 1 and 2, respectively, rendering them as some of the best-performing air-stable SIMs amongst the class of SIMs with D5h symmetry.
View Article and Find Full Text PDFSmall
December 2024
Department of Applied Physics and Center of Quantum Materials and Devices, Chongqing University, Chongqing, 401331, China.
The observation of both resonant quantum tunneling of magnetization (RQTM) and resonant quantum magnetodielectric (RQMD) effect in the perovskite multiferroic metal-organic framework [CHNH]Co(HCOO).is reported. An intrinsic magnetic phase separation emerges at low temperatures due to the hydrogen-bond-modified long-range super-exchange interaction, leading to the coexistence of canted antiferromagnetic order and single-ion (Co) magnets.
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