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PGI Kolloquium:

Prof. Dr. Annie K. Powell,
Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany

PGI Lecture Hall, Building 04.8, 2nd Floor, Room 365

26.10.2018 11:00 Uhr

Approaching a Quantum Critical Point Using Chemical Means – a Science Fiction Wormhole in a Science Fact Scenario

PowellCopyright: Prof. Dr. Powell

We have been developing ways to take the next steps in 3d/4f chemistry by cyclising small 3d/4f units to create “trapped infinite chains”. The idea of cyclising subunit building blocks to supply added cooperativity to the system takes its inspiration from the added value of cyclising a finite peptide chain or creating an aromatic ring system which show different properties from their simple chain precursors.

In a similar way, we take smaller building blocks of 3d/4f units and cyclise them to create added value in electronic and magnetic terms. This presentation describes how the cyclisation of a building block – best described as an {FeLnFeLn} building block - into a ring containing 20 metal ions composed of 5 such units being joined together as {FeLnFeLn}5.[1] Such a system allows us – so far shown for the Ln = Gd case - to be very close to, or possibly at, a Quantum Critical Point (QCP) for this system.

What this means is that there are a huge number of accessible ground states needing no energy to move between them. If we actually sit at the QCP the number of accessible states is infinite – which is like the possibilities for the science fiction proposal of using wormholes to access the infinite number of possible Universes resulting from the Big Bang.

This chemical pathway to approaching or even sitting at a QCP creates a new paradigm for the future of molecular-based materials. Amongst other things, such as the huge magnetic ground state and its applications which will be discussed in this talk, there is the tantalising idea of moving information processing which is currently based on “Yes and No” - i.e. “Black and White” binary logic - to a scenario of “Infinite Shades of Grey”.

[1] High spin cycles: topping the spin record for a single molecule verging on quantum criticality, A. Baniodeh, N. Magnani, Y. Lan, G. Buth, C. E. Anson, J. Richter, M. Affronte, J. Schnack, A. K. Powell, npj Quantum Materials (2018) 3:10 ; doi:10.1038/s41535-018-0082-7


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