We present a unified description of the response of the hyperhoneycomb Kitaev magnet β-Li2IrO3 to applied
magnetic fields along the orthorhombic directions a, b, and c. This description is based on the minimal nearest-neighbor J-K- model and builds on the idea that the incommensurate counter-rotating order observed experimentally at zero field can be treated as a long-distance twisting of a nearby commensurate order with six
spin sublattices. The results reveal that the behavior of the system for Ha, Hb, and Hc share a number of qualitative features, including (i) a strong intertwining of the modulated, counter-rotating order with a set of uniform orders; (ii) the disappearance of the modulated order at a critical field H∗, whose value is strongly
anisotropic with H∗b ≤H∗a ; (iii) the presence of a robust zigzag phase above H∗; and (iv) the fulfillment of the Bragg peak intensity sum rule. It is noteworthy that the disappearance of the modulated order for Hc proceeds via a “metamagnetic” first-order transition which does not restore all broken symmetries. This implies the existence of a second finite-T phase transition at higher magnetic fields. We also demonstrate that quantum fluctuations give rise to a significant reduction of the local moments for all directions of the field. The results for the total magnetization for Hb are consistent with available data and confirm a previous assertion that the system is very close to the highly frustrated K- line in parameter space. Our predictions for the magnetic response for fields along a and c await experimental verification.
Funding
U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award No. DE-SC0018056
History
School
Science
Department
Physics
Published in
Physical Review Research
Volume
2
Issue
1
Pages
013065
Publisher
American Physical Society
Version
VoR (Version of Record)
Publisher statement
This is an Open Access Article. It is published by American Physical Society under the Creative Commons Attribution 4.0 Unported Licence (CC BY). Full details of this licence are available at: http://creativecommons.org/licenses/by/4.0/