Abstract
Strong interplay of spin and charge/orbital degrees of freedom is the fundamental characteristic of the iron-based superconductors (FeSCs), which leads to the emergence of a nematic state as a rule in the vicinity of the antiferromagnetic state. Despite intense debate for many years, however, whether nematicity is driven by spin or orbital fluctuations remains unsettled. Here, by use of transport, magnetization, and 75As nuclear magnetic resonance (NMR) measurements, we show a striking transformation of the relationship between nematicity and spin fluctuations (SFs) in Na1-x Li x FeAs; For x ≤ 0.02, the nematic transition promotes SFs. In contrast, for x ≥ 0.03, the system undergoes a non-magnetic phase transition at a temperature T 0 into a distinct nematic state that suppresses SFs. Such a drastic change of the spin fluctuation spectrum associated with nematicity by small doping is highly unusual, and provides insights into the origin and nature of nematicity in FeSCs.
| Original language | English |
|---|---|
| Article number | 2139 |
| Journal | Nature Communications |
| Volume | 9 |
| Issue number | 1 |
| DOIs | |
| State | Published - Dec 1 2018 |
| Externally published | Yes |
Funding
This work was financially supported by the National Creative Research Initiative (2010-0018300) and Global Collaborative Research Projects (2016K1A4A3914691) through Korea’s NRF, which is funded by Ministry of Science, ICT and Future Planning (MSIP). The work at Germany has been supported by the Deutsche Forschungsgemeinschaft (Germany) via DFG Research Grants BA 4927/2-1. D.V.E. acknowledges VW-foundation for partial financial support.