Seminar: “Emergent quantum electrodynamics and magnetic Higgs phase in quantum spin ice" Shigeki Onoda, RIKEN

Theory of Quantum Matter Unit would like to invite you to a semiar  :

• Date/Time: Thu 14th Nov / 1:30-2:30pm
• Venue: D014, Lab1
• Speaker: Dr. Onoda Shigeki, RIKEN

“Emergent quantum electrodynamics and magnetic Higgs phase in quantum spin ice”

Dr. Shigeki Onoda, Senior Research Scientist,

Condensed Matter Theory Lab & Quantum Matter Theory Research Team, RIKEN

Thu, 14^th Nov at 13:30-14:30 in D014, Lab1

When a continuous symmetry of particles coupled to gauge fields is spontaneously broken, otherwise gapless (or massless) Nambu-Goldstone modes acquire an energy gap (or a mass) via the Higgs mechanism. Superconductivity provides a prototypical example in condensed matter. Namely, a broken U(1) gauge invariance of a global phase of Cooper pair wavefunctions coupled to electromagnetic gauge fields absorbs a Nambu-Goldstone mode into gapped collective electric charge excitations [2]. The Higgs phase has also been studied on lattice systems, whereas any real physical example has not been established in nature. I will present recent works on rare-earth (Pr, Tb, or Yb) magnetism associated in insulating pyrochlore oxides, dubbed as quantum spin ice, from both theoretical and experimental viewpoints. It is found that the low-temperature properties are well described by quantum dynamics of coupled bosonic spinons and gauge fields producing fictitious photons. It is likely that Pr2Zr2O7 is a "spinon insulator" with gapless "photons", namely, in a deconfined phase, while Yb2Ti2O7 is a "spinon superconductor", namely, in a Higgs phase exhibiting a magnetic long-range order.

We hope to see many of you there !

Shiho Saito, Theory of Quantum Matter Unit