Moment evolution across the ferromagnetic phase transition of giant magnetocaloric (Mn,Fe)2(P,Si,B) compounds

A strong electronic reconstruction resulting in a quenching of the Fe magnetic moments has recently been predicted to be at the origin of the giant magnetocaloric effect displayed by Fe2P-based materials. To verify this scenario, x-ray magnetic circular dichroism experiments have been carried out at the L edges of Mn and Fe for two typical...

Tuning the metamagnetic transition in the (Co, Fe)MnP system for magnetocaloric purposes

The inverse magnetocaloric effect taking place at the antiferro-to-ferromagnetic transition of (Co,Fe)MnP phosphides has been characterised by magnetic and direct ?Tad measurements. In Co0.53Fe0.47MnP, entropy change of 1.5?Jkg?1?K?1 and adiabatic temperature change of 0.6?K are found at room temperature for an intermediate field change (?B?=?1...

Second harmonic generation microscopy reveals hidden polar organization in fluoride doped MIL-53(Fe)

Polar metal–organic frameworks have potential applications as functional non-linear optical, piezoelectric, pyroelectric and ferroelectric materials. Using second harmonic generation microscopy we found that fluoride doping of the microporous iron(III) terephthalate MOF MIL-53(Fe) induces a polar organization in its structure, which was not...

Towards acid MOFs – catalytic performance of sulfonic acid functionalized architectures

In this work, the inclusion of free sulfonic acid groups in highly stable MOFs is explored. The synthesized catalysts have been applied in a model esterification reaction. Two metal organic frameworks bearing sulfonic acid moieties are investigated: HSO3-MIL-101(Cr) synthesized following different approaches and a new structure based on HSO3-bdc...

Taming the first-order transition in giant magnetocaloric materials

Large magnetically driven temperature changes are observed in MnFe(P,Si,B) materials simultaneously with large entropy changes, limited (thermal or magnetic) hysteresis, and good mechanical stability. The partial substitution of B for P in MnFe(P,Si) compounds is found to be an ideal parameter to control the latent heat observed at the Curie...

Wave Energy in Brittany (France)—Resource Assessment and WEC Performances

Refined numerical wave energy resource assessments are required to reduce uncertainties in the evaluation of available power and energy production. However, to restrict the computational cost, a great part of wave hindcast simulations cover a limited time range (below ten years) or rely on coarse spatial resolutions while routinely ignoring tide...

New and ambitious or just more of the same?: The Energy Union at a crossroads

Crystal structures and magnetic properties of Fe_1.93-xCo_xP_1-ySi_y compounds

In view of the interest that (Fe,Co)₂(P,Si) compounds have as potential permanent magnets, their structural and magnetic phase diagrams are explored focusing on establishing the range where the hexagonal Fe₂P-type structure is observed. In Fe_1.93-xCo_xP_1-ySi_y, the highest Si...

Drastic Influence of Synthesis Conditions on Structural, Magnetic, and Magnetocaloric Properties of Mn(Fe,Ni)(Si,Al) Compounds

Mn compounds presenting magneto-structural phase transitions are currently intensively studied for their giant magnetocaloric effect; nevertheless, several parameters remain to be further optimized. Here, we explore the Mn(Fe,Ni)(Si,Al) series, which presents two advantages. The Mn content is fixed to unity ensuring a large saturation...

(Fe,Co)₂(P,Si) rare-earth free permanent magnets: From macroscopic single crystals to submicron-sized particles

While rare-earth magnets exhibit unchallenged hard-magnetic properties, looking for alternatives based on inexpensive elements of non-critical supply remains of utmost interest. Here, we demonstrate that (Fe,Co)₂(P,Si) single crystals combine a large magnetocrystalline anisotropy (K₁ ≈ 0.9 MJ m⁻³ at 300 K),...

Investigating the Case of Titanium(IV) Carboxyphenolate Photoactive Coordination Polymers

The reactivity of 2,5-dihydroxyterephthalic acid (H₄DOBDC) with titanium(IV) precursors was thoroughly investigated for the synthesis of metal-organic frameworks under solvothermal conditions. Four crystalline phases were isolated whose structures were studied by a combination of single-crystal or powder X-ray diffraction and solid...

Spin Hall magnetoresistance in a canted ferrimagnet

We study the spin Hall magnetoresistance effect in ferrimagnet/normal metal bilayers, comparing the response in collinear and canted magnetic phases. In the collinear magnetic phase, in which the sublattice magnetic moments are all aligned along the same axis, we observe the conventional spin Hall magnetoresistance. In contrast, in the canted...

Efficient Room-Temperature Cooling with Magnets

Magnetic cooling is a highly efficient refrigeration technique with the potential to replace the traditional vapor compression cycle. It is based on the magnetocaloric effect, which is associated with the temperature change of a material when placed in a magnetic field. We present experimental evidence for the origin of the giant entropy...