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Methods

We collect data on samples that are both synthesized by ourselves and by external partners. We have different equipment at the Department of Chemistry, which we regularly use to collect relevant data for magnetic testing, including:

Single-crystal X-ray diffraction: We routinely measure structural parameters of crystalline samples at liquid nitrogen temperatures, but we can also do experiments under non-standard conditions, such as high pressure (typically up to 10 kbar), liquid Helium temperatures and under light irradiation (both with laser and LED light sources). In many cases, we may even collect data of sufficient quality to carry out investigations of electron density. The combination of all these options is unique in Denmark.

Magnetic measurements: temperature-dependent magnetic susceptibility and field-dependent magnetization measurements are performed using a Quantum Design PPMS, which is further equipped with apparatus for the recovery of helium gas, allowing continuous operation.

In addition to our in-house equipment, we collaborate closely with researchers at major experimental facilities in Japan, the United States, and France. We regularly make advanced experiments at these facilities, including:

Synkrotron X-ray diffraction: the immense intensity that is available at synchrotrons provides access to data of unmatched high resolution and quality. We use this for detailed electron density determination.

Non-polarized neutron diffraction: a precise determination of the (anisotropic) atomic thermal parameters is often not possible from X-ray diffraction alone (especially for hydrogen atoms), but may nonetheless be necessary to achieve an accurate electron density. Neutron diffraction is a reliable alternative method for determining these nuclear parameters, but requires crystals of magnitude 1-10 mm3. When such crystals are available, we use neutron diffraction as far as possible to provide us with information about the atomic thermal parameters.

Polarized neutron diffraction (PND): PND is a technique that allows the determination of spin density in a material. This means that we get acquainted with the distribution of magnetic torque in the material (spin delocalisation), as well as the sign of the torque (spin polarisation), and its spatial distribution around the atoms (in which orbital are the unpaired electrons staying). We are particularly interested in using this technique to directly visualize exchange pathways in coupled magnetic systems as well as look at the spin density in lanthanide-containing molecular systems.