Energy transfer

Fig. 1. Magnetic cooling principle demonstrated in terms of the spin and phonon systems of a solid. The application of the magnetic field leads to the alignment of spins and reduces the magnetic entropy Smag. Under adiabatic conditions (the total entropy is constant), the reduction in the magnetic entropy is compensated by an increase in the phonon part of the entropy Sph, i.e. by intensified lattice vibration (see a largely exaggerated phonon wave in step I). As a result of the increased lattice vibration the temperature rises. The evolved heat is removed from the system to the environment (step II). On thermal isolation of the solid from the environment and removal of the magnetic field, the spins randomise causing an increase in Smag and the corresponding reduction in Sph (step III). This step leading to the temperature reduction forms the basis of the magnetic cooling. Image taken from Julia Lyubina 2017 J. Phys. D: Appl. Phys. 50 053002, © IOP Publishing, All Rights Reserved.

Magnetic cooling: how cool is that!

By Dean Williams on February 17, 2017

More than 15 % of energy is spent worldwide on various forms of cooling. In addition to the energy bill, the compressor in cooling units can bring a rich palette of sounds to your home: think of all this clanking,… Read More ›

Schematization of the electronic structure of perylene and graphene and the arrangements of the components in the hybrid structure. The spatial separation between the graphene crystal and the perylene molecules is also indicated (d). Note that perylene and graphene are coupled via near-field electromagnetic interaction and the electronic wave functions are separated by the insulating PMMA layer.

Spectacularly long range energy transfer to graphene

By Dean Williams on August 2, 2016

Can graphene be used as a nanoscopic ruler over a wide range of distances?

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Energy transfer

Magnetic cooling: how cool is that!

Spectacularly long range energy transfer to graphene