IQ / QM Canada : Natalia Perkins

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Sur Zoom https://us02web.zoom.us/j/9878458456

Mot de passe: 3 chiffres pour l’inverse de la constante destructure fine : 137

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             Natalia Perkins

Départementde physique, Université du Minnesota

Mardi,le 2 mars, 2021

11:00Heure normale de l’ouest (GMT -08:00)

14:00Heure normale de l’est (GMT -05:00)

Disorder upon disorder:localization effects in the Kitaev spin liquid,

Résumé: One of the long-standing openproblems which recently attracted a lot of attention is understanding howa quantum spin liquid (QSL) state responds to various forms of disorder,such as dislocations, vacancies, impurities, and bond randomness, which areinevitable in real materials. It has been noted that quenched disorder on topof the quantum disordered strongly correlated spin state of a QSL can giverise to diverse and often puzzling behaviors. In my talk, I will focus onthe impact of disorder on the properties of the Kitaev QSL, which isrealized in a system of spin-1/2 at sites of a honeycomblattice interacting via Ising-like frustrated nearest-neighbor exchangeinteractions. This model is exactly solvable, has a QSLground state, and is yetrealistic. One of the most exciting features of the Kitaev QSL is thefractionalization of spin excitations into itinerant Majorana fermionsand static Z2 fluxes. The fact that the Majorana fermionsin the Kitaev model are non-interacting and that this remains true even inthe presence of various types of quenched disorder, makes the Kitaev QSL anideal setting for exploringnovel disorder-induced localization effects on aquantitative level. In this work, we consider three types of disorder inthe Kitaev model: the bond disorder, the site disorder and thethermal disorder. I will also discuss the effect of disorder onthe low-temperature behavior of the 5d-electron compound H3LiIr2O6,which has shown to be a strong candidate for Kitaev physics consideringthe absence of any signs of a long-range ordered magnetic state. I will show thata finite density of random vacancies in the Kitaev model gives rise to astriking pileup of low-energy Majorana eigenmodes and reproduces the apparentpower-law upturn in the specific heat measurements of H3LiIr2O6.