Disorder effects in the Kitaev spin liquid*

Recently, the 5d-electron compound H3LiIr2O6 [1] has shown to be a strong candidate for Kitaev spin liquid [2] considering the absence of any signs of a long-range ordered magnetic state. In my talk I will discuss the role of disorder in the Kitaev spin liquid and its relevance to the experimental observations in H3LiIr2O6 [3,4]. Our findings suggest that a finite density of random vacancies in the Kitaev model give rise to a striking pileup of low-energy Majorana eigenmodes and reproduces the apparent power-law upturn in the specific heat measurements of H3LiIr2O6 [1]. Physically, the vacancies can originate from various sources such as missing magnetic moments or the presence of non-magnetic impurities (true vacancies), or from local weak couplings of magnetic moments due to strong but rare bond randomness (quasivacancies). We show numerically that the vacancy effect is readily detectable even at low vacancy concentrations and that it is not very sensitive neither to the nature of vacancies nor to different flux backgrounds.


[1] K. Kitagawa, T. Takayama, Y. Matsumoto, A. Kato, R. Takano,Y. Kishimoto, S. Bette, R. Dinnebier, G. Jackeli, and H. Takagi, Nature 554, 341 (2018).

[2] A. Kitaev, Annals of Physics 321, 2 (2006).

[3] J. Knolle, R. Moessner, and N. B. Perkins, Phys. Rev. Lett.122, 047202 (2019).

[4] W.-H. Kao, J. Knolle, G. B. Halasz, R. Moessner, and N. B. Perkins, arxiv:2007.11637.