Spin correlations in (Mn,Fe)2(P,Si) magnetocaloric compounds above Curie temperature

The longitudinal-field muon-spin relaxation (LF-μSR) technique was employed to study the spin correlations in (Mn,Fe)2(P,Si) compounds above the ferromagnetic transition temperature (TC). The (Mn,Fe)2(P,Si) compound under study is found to show itinerant magnetism. The standard deviation of the magnetic field distribution of electronic origin...

Short-range magnetic correlations and spin dynamics in the paramagnetic regime of (Mn,Fe)2(P,Si)

The spatial and temporal correlations of magnetic moments in the paramagnetic regime of (Mn,Fe)2(P,Si) have been investigated by means of polarized neutron diffraction and muon-spin relaxation techniques. Short-range magnetic correlations are present at temperatures far above the ferromagnetic transition temperature (TC). This leads to...

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...

Kinetic-arrest-induced phase coexistence and metastability in (Mn,Fe)2(P,Si)

Neutron diffraction, Mössbauer spectroscopy, magnetometry, and in-field x-ray diffraction are employed to investigate the magnetoelastic phase transition in hexagonal (Mn,Fe)2(P,Si) compounds. (Mn,Fe)2(P,Si) compounds undergo for certain compositions a second-order paramagnetic (PM) to a spin-density-wave (SDW) phase transition before further...

Switching the magnetostructural coupling in MnCoGe-based magnetocaloric materials

We performed neutron-diffraction experiments and density functional theory calculations to study the magnetostructural coupling in MnCoGeBx (x=0, 0.01, and 0.05) alloys. By varying the amount of boron addition, we are able to freely switch the magnetostructural coupling on and off in the MnCoGe alloys. It is found that the boron addition...

Magnetocaloric effect in the (Mn,Fe)₂(P,Si) system: From bulk to nano

In the field of nanoscale magnetocaloric materials, novel concepts like micro-refrigerators, thermal switches, microfluidic pumps, energy harvesting devices and biomedical applications have been proposed. However, reports on nanoscale (Mn,Fe)₂(P,Si)-based materials, which are one of the most promising bulk materials for solid-state...

Enhanced reversibility of the magnetoelastic transition in (Mn,Fe)₂(P,Si) alloys via minimizing the transition-induced elastic strain energy

Magnetocaloric materials undergoing reversible phase transitions are highly desirable for magnetic refrigeration applications. (Mn,Fe)₂(P,Si) alloys exhibit a giant magnetocaloric effect accompanied by a magnetoelastic transition, while the noticeable irreversibility causes drastic degradation of the magnetocaloric properties...