Physics Colloquium: The Fate of Magnetism in Matter at Extreme Conditions of Density

Abstract: 

Magnetism in materials composed of transition-metal ions, either metallic or insulators, is a consequence of the strong d-d- correlation states. Those states governed by Hund's rules can be manipulated to produce magnetic material from the nano to the mega scales. It will be shown how magnetism can be deteriorated and eventually destroyed at very high pressures. This mechanism is experimentally studied using high-pressure devices: Diamond Anvil Cells, which allows achieving pressures to 10^6 bars. Methods such as Synchrotron X-ray diffraction, 57Fe nuclear gamma resonance, and electrical conductivity are employed to elucidate the various mechanisms such as the pressure dependence of the 5d spin states and the pressure induced Mott-Hubbard correlation collapse. Following a short introduction of the methodology, examples of several Fe-oxide materials will be presented.

Seminar Organisers: Dr. Tomer Volansky, Dr. Dovi Poznanski