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Dipartimento di Fisica e Scienze della Terra

Parma Research on MAgnetism


Magnets are ubiquitous in modern life: they are key components in sensors, actuators, motors, appliances, computers, cars. PaRMa is the home of the DiFeST expertise in magnetism. Theorists, material scientists and experimental physicists join efforts on the following main topics:

Magnetic molecules, that provide the playground for understanding the basic magnetic phenomena, are at the same time very promising candidates for advanced applications such as the future quantum computers, orders of magnitude more powerful than present ones, as well as green magnetic refrigerators.

 

Left: The characteristic low temperature hysteresis cycle of a magnetic molecule (here the molecule known as Fe8). Steps indicate that at the corresponding field values the energy levels of the molecule display avoided crossings, where the magnetic state changes its quantum nature, increasing or decreasing the magnetic moment by fixed amounts.

Multiferroics are interesting materials where at least two ferroic orders (among ferroelectricity, ferromagnetism and ferroelasticity) coexist. In particular magnetoelectric (ME) multiferroics could achieve a valuable technological impact, allowing the realization of multifunctional devices exploiting more than one task at a time. Moreover, understanding the conditions of coexistence of magnetism and ferroelectricity is a challenging task, while the comprehension of their complex coupling mechanisms is a completely open issue.

 

Right: The Bi1-x/3(Mn3III)(Mn4-xIIIMnxIV)O12 system displays a composition dependent polymorphisms related to dramatic differences of the multiferroic properties. The magnetic behaviour of the three polymorphs (monoclinic, rhombohedral and cubic) is peculiar and can be explained by the presence of a strong magnetoelectric coupling that decreases by decreasing the polar character.

 

Unconventional superconductors, that carry electric currents without resistance, and are invariably found to be close to a magnetic state (a closely similar material is a magnet). The theory that explains why this happens is yet to be written, but the effort to understand how they work is highly rewarding in case of success. If we could design new materials with tailored properties we would transfer power without dissipation and we could extensively implement superconducting magnets in the techologies described at the top.

Left: SmFeAsO is an antiferromagnet below TN=140 K. Charge-doped SmFeAsO0.89F0.11 is a superconcuctor below Tc=53 K. When Fe (normally a magnetic ion) is substituted partially by Ru (a non magnetic ion with the same number of valence electrons), surprisingly, the compound reverts to a magnetic state, coexisting with low temperature superconductivity. Transitions detected by µSR.

 

 

Here is a list of more detailed topics: