A5082407363- Crystallization and Solubility Studies
- X-ray Diffraction in Crystallography
- Magnetism in coordination complexes
- Lanthanide and Transition Metal Complexes
- Physics of Superconductivity and Magnetism
- Advanced Condensed Matter Physics
- Organic and Molecular Conductors Research
- Electron Spin Resonance Studies
- Quantum and electron transport phenomena
- Advanced NMR Techniques and Applications
- Crystallography and molecular interactions
- Porphyrin and Phthalocyanine Chemistry
- Advanced Chemical Physics Studies
- Non-Destructive Testing Techniques
- Magnetic properties of thin films
- Diamond and Carbon-based Materials Research
- Graphene research and applications
- Multiferroics and related materials
- Carbon Nanotubes in Composites
- Advanced MRI Techniques and Applications
- Geophysical and Geoelectrical Methods
- Quantum many-body systems
- Magnetic Properties and Applications
- ZnO doping and properties
- Ferroelectric and Piezoelectric Materials
University of Manchester
2020-2025
University of Warwick
2019-2021
University of Bern
2016
The use of magnetisation decay measurements to characterise very slow relaxation the in single-molecule magnets is becoming increasingly prevalent as times move longer timescales outside AC susceptibility range. However, experimental limitations and a poor understanding distribution underlying stretched exponential function, commonly used model data, may be leading misinterpretation results. Herein we develop guidelines on design, data fitting, analysis required accurately interpret...
Abstract Single-molecule magnets are among the most promising platforms for achieving molecular-scale data storage and processing. Their magnetisation dynamics determined by interplay between electronic vibrational degrees of freedom, which can couple coherently, leading to complex vibronic dynamics. Building on an ab initio description Hamiltonians, we formulate a non-perturbative model low-energy magnetic freedom in monometallic single-molecule magnets. Describing their low-temperature...
Isolated dysprosocenium cations, [Dy(CpR)2]+ (CpR = substituted cyclopentadienyl), have recently been shown to exhibit superior single-molecule magnet (SMM) properties over closely related complexes with equatorially bound ligands. However, gauging the crossover point at which CpR substituents are large enough prevent equatorial ligand binding, but small approach metal and generate strong crystal field splitting has required laborious synthetic optimization. We therefore created computer...
Most of the work in expanding frontiers single-molecule magnets employs chemical design new molecules to increase size effective barrier (Ueff) or hysteresis temperature (TH). Here we explore how perturbing local environment affects magnetic relaxation properties by dissolving [Dy(Cpttt)2][B(C6F5)4] two different solvents: difluorobenzene (DFB) and dichloromethane (DCM). Surprisingly, find no significant effects phonon-driven Raman-I regime at higher temperatures, but do observe that...
The accurate electron density distribution and magnetic properties of two metal-organic polymeric magnets, the quasi-one-dimensional (1D) Cu(pyz)(NO3)2 quasi-two-dimensional (2D) [Cu(pyz)2(NO3)]NO3·H2O, have been investigated by high-resolution single-crystal X-ray diffraction functional theory calculations on whole periodic systems selected fragments. Topological analyses, based quantum atoms in molecules, enabled characterization possible exchange pathways establishment relationships...
The hexagonal-bipyramidal lanthanide(III) complex [Dy(OtBu)Cl(18-C-6)][BPh4] (1; 18-C-6 = 1,4,7,10,13,16-hexaoxacyclooctadecane ether) displays an energy barrier for magnetization reversal (Ueff) of ca. 1000 K in a zero direct-current field. Temperature-dependent X-ray diffraction studies 1 down to 30 reveal bending the Cl–Ln–OtBu angle at low temperature. Using ab initio calculations, we show that significant O–Dy–Cl upon cooling from 273 100 leads 10% decrease excited electronic states. A...
Magnetite has long been investigated across many disciplines due to the interplay between its ferroic order parameters, namely, ferrimagnetism, ferroelasticity, and ferroelectricity. Despite this, experimental difficulty in measuring low temperature real space images of ferroelectric domains meant that local behavior emergent below ∼38 K phase transition have yet be realized. This work presents uses piezoresponse force microscopy as a function probe onset piezoelectricity ferroelectricity 38...
We examine the crystal structures and magnetic properties of several S = 1 Ni(II) coordination compounds, molecules polymers, that include bridging ligands HF2−, AF62− (A Ti, Zr) pyrazine or non-bridging F−, SiF62−, glycine, H2O, 1-vinylimidazole, 4-methylpyrazole 3-hydroxypyridine. Pseudo-octahedral NiN4F2, NiN4O2 NiN4OF cores consist equatorial Ni-N bonds are equal to slightly longer than axial Ni-Lax bonds. By design, zero-field splitting (D) is large in these systems and, presence...
We perform magnetization sweeps on the high-performing single-molecule magnet [Dy(Cpttt)2][B(C6F5)4] (Cpttt = C5H2tBu3-1,2,4; tBu C(CH3)3) to determine quantum tunneling gap of ground-state avoided crossing at zero-field, finding a value order 10-7 cm-1. In addition pure crystalline material, we also measure tunnel splitting dissolved in dichloromethane (DCM) and 1,2-difluorobenzene (DFB). find that concentrations 200 or 100 mM these solvents increases size compared sample, despite...
The molecular coordination complex NiI$_2$(3,5-lut)$_4$ [where (3,5-lut) $=$ (3,5-lutidine) (C$_7$H$_9$N)] has been synthesized and characterized by several techniques including synchrotron X-ray diffraction, ESR, SQUID magnetometry, pulsed-field magnetization, inelastic neutron scattering muon spin relaxation. Templated the configuration of 3,5-lut ligands molecules pack in-registry with Ni--I$\cdots$I--Ni chains aligned along $c$--axis. This arrangement leads to through-space I$\cdots$I...
Dysprosium single-molecule magnets (SMMs) with two mutually trans- anionic ligands have shown large crystal field (CF) splitting, giving record effective energy barriers to magnetic reversal (Ueff) and hysteresis temperatures (TH). However, these complexes tend be bent, imposing a transverse that reduces the purity of mJ projections CF states promotes relaxation. A complex only one ligand could more pure states, thus high Ueff TH. Here we report first example an SMM this topology,...
We report on a comprehensive characterization of the newly synthesized ${\mathrm{Cu}}^{2+}$-based molecular magnet $[\mathrm{Cu}{(\mathrm{pz})}_{2}{(2\text{\ensuremath{-}}\mathrm{HOpy})}_{2}]{({\mathrm{PF}}_{6})}_{2}$ (CuPOF), where $\mathrm{pz}={\mathrm{C}}_{4}{\mathrm{H}}_{4}{\mathrm{N}}_{2}$ and $2\text{\ensuremath{-}}\mathrm{HOpy}={\mathrm{C}}_{5}{\mathrm{H}}_{4}\mathrm{NHO}$. From comparison theoretical modeling to results bulk magnetometry, specific heat,...
The use of magnetisation decay measurements to characterise very slow relaxation the in single-molecule magnets are becoming increasingly prevalent as times move longer timescales outside AC susceptibility range. However, experimental limitations and a poor understanding distribution underlying stretched exponential function, commonly used model data, may be leading misinterpretation results. Herein we develop guidelines on design, data fitting, analysis required accurately interpret...
Abstract Although low-dimensional S = 1 antiferromagnets remain of great interest, difficulty in obtaining high-quality single crystals the newest materials hinders experimental research this area. Polycrystalline samples are more readily produced, but there inherent problems extracting magnetic properties anisotropic systems from powder data. Following a discussion effect powder-averaging on various measurement techniques, we present methodology to overcome issue using thermodynamic...
We present the magnetic properties of a new family S = 1 molecule-based magnets, NiF2(3,5-lut)4·2H2O and NiX2(3,5-lut)4, where X HF2, Cl, Br, or I (lut lutidine C7H9N). Upon creation isolated Ni-X···X-Ni Ni-F-H-F···F-H-F-Ni chains separated by bulky nonbridging ligands, effect that halogen substitution has on transition-metal-ion complexes can be investigated directly in isolation from competing processes such as Jahn-Teller distortions. find larger halide ions turns increasingly strong...
We present an investigation of the effect randomizing exchange coupling strengths in $S=1/2$ square lattice quasi-two-dimensional quantum Heisenberg antiferromagnet (QHAF) ${(\mathrm{QuinH})}_{2}\mathrm{Cu}{({\mathrm{Cl}}_{x}{\mathrm{Br}}_{1\ensuremath{-}x})}_{4}\ifmmode\cdot\else\textperiodcentered\fi{}2{\mathrm{H}}_{2}\mathrm{O}$ (QuinH $=$ Quinolinium, ${\mathrm{C}}_{9}{\mathrm{H}}_{8}{\mathrm{N}}^{+}$), with $0\ensuremath{\le}x\ensuremath{\le}1$. Pulsed-field magnetization measurements...
We show that fluorobenzene-bound dicationic lanthanide complexes containing a single anionic ligand can interesting single-molecule magnet properties, and be useful starting materials to heteroleptic bulky ligands.
Magnetite has long been investigated across many disciplines due to the interplay between its ferroic order parameters, namely ferrimagnetism, ferroelasticity and ferroelectricty. Despite this, experimental difficulty in measuring low temperature real space images of ferroelectric domains meant that local behaviour emergent below 38 K phase transition have yet be realised. This work presents domains, uses piezo force microscopy to, as a function temperature, probe onset piezoelectricty...
Isolated dysprosocenium cations, [Dy(CpR)2]+ (CpR = substituted cyclopentadienyl), have recently been shown to exhibit superior single-molecule magnet (SMM) properties over closely related complexes with equatorially-bound ligands. However, gauging the crossover point at which CpR substituents are large enough prevent equatorial ligand binding, but small approach metal and generate strong crystal field splitting, has required laborious synthetic optimization. We therefore created computer...