Seminar by Olga Sikora: “Quantum Spin Ice : Monte Carlo simulations"

Theory of Quantum Matter (Nic Shannon) Unit would like to invite you to a seminar by Dr. Olga Sikora, Department of Physics at National Taiwan University.

• Date: Fri, April 4
• Time: 14:00-15:00
• Venue: D014, Level D, Lab1

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Quantum Spin Ice : Monte Carlo simulations

Olga Sikora, Department of Physics, National Taiwan University

Classical spin ice models - in which spin directions are bound to the same rules as protons in water ice - are widely discussed as condensed matter systems with unusual ground states supporting deconfinement of magnetic monopoles. However, the role of quantum effects in spin ice materials and the nature of their equilibrium ground state remains an open question. I will demonstrate our numerical study of the phase diagram of a quantum ice model with tunnelling between configurations. We found compelling evidence for the existence of an extended quantum spin-liquid phase with photon-like excitations. 

I will also discuss an extended quantum spin ice model with long-range dipolar interactions, and competing second-neighbour exchange taken into account. We investigate the competing ordered ground states, and using a combination of exact diagonalization and zero-temperature quantum Monte Carlo simulations we establish that, for a realistic choice of parameters, only a very small amount of quantum tunnelling is needed to convert an ordered ground state into a quantum spin liquid. 

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We look forward to seeing you at the venue !