Accurate and unequivocal determination of the crystal-field parameters of lanthanide ions via a multitechnique approach

Understanding the crystal field of lanthanide complexes is pivotal for the testing of Stevens operator equivalents and the development of lanthanide-based molecular magnets. Intense theoretical investigation is aimed at the determination of the Hamiltonian parameters, but accurate experimental tests often suffer from overparametrization. Because of this, clear-cut experimental determinations are missing even high-symmetry environments. Here we present a detailed study of the crystal-field parameters of Pr(III) ions in a high-symmetry environment, using the cyano-based molecular magnetic material Pr[Co(CN)6] · 5H2O. The problem of multiple solutions is considered with particular detail, and we show how unequivocal determination of the parameters becomes possible only by combining different spectroscopic and magnetometric techniques. Eventually we compare the solution with fitting methodologies that are commonly employed and we highlight the level of information that can be gained by such procedures

Accurate and unequivocal determination of the crystal-field parameters of lanthanide ions via a multitechnique approach

Understanding the crystal field of lanthanide complexes is pivotal for the testing of Stevens operator equivalents and the development of lanthanide-based molecular magnets. Intense theoretical investigation is aimed at the determination of the Hamiltonian parameters, but accurate experimental tests often suffer from overparametrization. Because of this, clear-cut experimental determinations are missing even high-symmetry environments. Here we present a detailed study of the crystal-field parameters of Pr(III) ions in a high-symmetry environment, using the cyano-based molecular magnetic material Pr[Co(CN)6] · 5H2O. The problem of multiple solutions is considered with particular detail, and we show how unequivocal determination of the parameters becomes possible only by combining different spectroscopic and magnetometric techniques. Eventually we compare the solution with fitting methodologies that are commonly employed and we highlight the level of information that can be gained by such procedures

Chiral Nanomagnets

We report on the enhanced optical properties of chiral magnetic nanohelices with critical dimensions comparable to the ferromagnetic domain size. They are shown to be ferromagnetic at room temperature, have defined chirality, and exhibit large optical activity in the visible as verified by electron microscopy, superconducting quantum interference device (SQUID) magnetometry, natural circular dichroism (NCD), and magnetic circular dichroism (MCD) measurements. The structures exhibit magneto-chiral dichroism (MChD), which directly demonstrates coupling between their structural chirality and magnetism. A chiral nickel (Ni) film consisting of an array of nanohelices ∼100 nm in length exhibits an MChD anisotropy factor gMChD ≈ 10–4 T–1 at room temperature in a saturation field of ∼0.2 T, permitting polarization-independent control of the film’s absorption properties through magnetic field modulation. This is also the first report of MChD in a material with structural chirality on the order of the wavelength of light, and therefore the Ni nanohelix array is a metamaterial with magnetochiral properties that can be tailored through a dynamic deposition process

Magneto-optické měření monovrstev molekulárních nanomagnetů

We report field-dependent magnetization measurements on monolayers of [Dy(Pc)2] on quartz, prepared by the Langmuir–Blodgett technique. The films are thoroughly characterized by means of X-ray reflectivity and atomic force microscopy. The magnetisation of the sample is measured through the magnetic circular dichroism of a ligand-based electronic transition.V práci ukazujeme , že jsme dosáhli citlivosti jedné monovrstvy molekulárních magnetů DyPc2 pomocí magnetického cirkulárního dichroizmu

A four-coordinate cobalt(II) single-ion magnet with coercivity and a very high energy barrier

Single-molecule magnets display magnetic bistability of molecular origin, which may one day be exploited in magnetic data storage devices. Recently it was realised that increasing the magnetic moment of polynuclear molecules does not automatically lead to a substantial increase in magnetic bistability. Attention has thus increasingly focussed on ions with large magnetic anisotropies, especially lanthanides. In spite of large effective energy barriers towards relaxation of the magnetic moment, this has so far not led to a big increase in magnetic bistability. Here we present a comprehensive study of a mononuclear, tetrahedrally coordinated cobalt(II) single-molecule magnet, which has a very high effective energy barrier and displays pronounced magnetic bistability. The combined experimental-theoretical approach enables an in-depth understanding of the origin of these favourable properties, which are shown to arise from a strong ligand field in combination with axial distortion. Our findings allow formulation of clear design principles for improved materials

Determination of the electronic structure of a dinuclear dysprosium single molecule magnet without symmetry idealization

10.1039/C8SC03170CChemical Science1072101-211

Correction: Determination of the electronic structure of a dinuclear dysprosium single molecule magnet without symmetry idealization (Chemical Science (2019) 10 (2101–2110) DOI: 10.1039/C8SC03170C)

10.1039/C9SC90051AChemical Science10113429