Effect of structural disorder on the Kitaev magnet Ag3LiIr2O6

Abstract

The search for an ideal Kitaev spin liquid candidate with anyonic excitations and long-range entanglement has motivated the synthesis of a new family of intercalated Kitaev magnets such as H 3 LiIr 2 O 6 , Cu 2 IrO 3 , and Ag 3 LiIr 2 O 6 . The absence of a susceptibility peak and a two-step release of the magnetic entropy in these materials have been proposed as evidence of proximity to the Kitaev spin liquid. Here we present a comparative study of the magnetic susceptibility, heat capacity, and muon spin relaxation (μSR) between two samples of Ag 3 LiIr 2 O 6 in the clean and disordered limits. In the disordered limit, the absence of a peak in either susceptibility or heat capacity and the lack of zero-field muon precession in the μSR signal give the impression of a proximate spin liquid state. However, in the clean limit, peaks are resolved in both susceptibility and heat capacity, and spontaneous oscillations appear in the μSR signal, confirming long-range antiferromagnetic order in the ground state. The μSR oscillations fit to a Bessel function, characteristic of incommensurate order, as reported in the parent compound α-Li 2 IrO 3 . Our results clarify the role of structural disorder in the intercalated Kitaev magnets.

Unusual spin dynamics in the low-temperature magnetically ordered state of Ag3LiIr2O6

“…Consequently, the inference of the high-temperature peak (position and magnitude) and that of a two-step entropy release is rather insecure, let alone ascribing it to Majorana excitations. We note here that an even more recent report [29] has found evidence for magnetic ordering in a cleaner batch of samples in line with our observations. The remainder of the paper is organized as follows: we start by giving the details on the structure of ALIO and relevant technical details on measurements and theoretical methods in Sec.…”

“…In Refs. [28,29], the authors have made use of Ag 3 LiSn 2 O 6 (ALSO) as the nonmagnetic analog. However, it appears that no correction has been applied before subtracting these data from the measured heat capacity of ALIO.…”

Quantum materials with strong spin–orbit coupling: challenges and opportunities for materials chemists

“…128 Another clear example of the effect of stacking faults on physical properties may be found in the layered honeycomb iridates and ruthenates, a case in point being Ag 3 LiIr 2 O 6 , for which samples show ordering or an absence of ordering depending on the level of faulting. 129,130 Complementary techniques such as electron microscopy have the potential to accelerate our understanding of, and ability to control, stacking fault disorder. 71 Furthermore, efforts to study and control stacking faults in α-Li 2 IrO 3 and relatives are paralleled by current efforts in the energy materials field with regard to e.g.…”

Probing signatures of fractionalization in the candidate quantum spin liquid Cu2IrO3 via anomalous Raman scattering

“…Unlike H 3 LiIr 2 O 6 , however, the synthesis of Ag 3 LiIr 2 O 6 and Cu 2 IrO 3 can be controlled to reduce the disorder. For example, while disordered Ag 3 LiIr 2 O 6 samples with Ag randomly occupying voids of the LiIr 2 O 6 honeycomb layers show broad features in the heat capacity at low temperatures, higher-quality samples which do not have this Ag positional disorder actually undergo long-ranged magnetic order [44]. For Cu 2 IrO 3 as well, disorder can lead to measurable consequences.…”