Physics - Condensed Matter Seminar

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Condensed Matter Seminar - "Journeys in quantum magnets, from nodal lines to chiral stripes"

Event Type
Seminar/Symposium
Sponsor
Physics - Condensed Matter
Location
ESB 190
Date
Nov 22, 2024   1:00 pm  
Speaker
Kemp Plumb, Brown University
Contact
Stephen Bullwinkel
E-Mail
bullwink@illinois.edu
Phone
217-333-1652
Views
58

Competing interactions in frustrated magnets can result  in  highly degenerate ground states from which correlated liquid-like states of matter often emerge. In the extreme quantum limit,  these degenerate classical states may evolve into quantum spin liquids.  It is for this reason that frustrated magnets occupy a major area of quantum materials research. However, even when a quantum spin liquid is not realized – as is usually the case –  new collective physics often emerges from frustration.   In this talk, I will discuss two examples where magnetic frustration fails to give way to a quantum spin liquid, but results in unanticipated phenomena.   I will first present resonant x-ray scattering measurements on a metallic triangular lattice material that reveal a novel scalar chiral stripe magnetic ordering. The observed magnetic ordering is the origin of a previously unexplained giant anomalous Hall response in this material and arises from four-spin magnetic interactions that are frustrated in momentum space. The second example I will present is our discovery of a nodal line classical spin liquid on the face centered cubic lattice in K2IrCl6.  The nodal line spin liquid is highly susceptible to small perturbations that cause K2IrCl6 to magnetically order at low temperatures.  However, a proximity to the nodal line spin liquid dramatically enhances quantum fluctuations that dictate the thermodynamics of this material  and, contrary to the usual expectation, stabilize magnetic order by self-consistently generating an excitation gap. Through the above examples I hope to give a sense of how, when it comes to frustrated magnets, it is as much about the journey as it is the destination.

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