A series of LiFe1−xCoxAs compounds with different Co concentrations have been studied by transport, optical spectroscopy, angle-resolved photoemission spectroscopy and nuclear magnetic resonance. We observed a Fermi liquid to non-Fermi liquid to Fermi liquid (FL-NFL-FL) crossover alongside a monotonic suppression of the superconductivity with increasing Co content. In parallel to the FL-NFL-FL crossover, we found that both the low-energy spin fluctuations and Fermi surface nesting are enhanced and then diminished, strongly suggesting that the NFL behavior in LiFe1−xCoxAs is induced by low-energy spin fluctuations which are very likely tuned by Fermi surface nesting. Our study reveals a unique phase diagram of LiFe1−xCoxAs where the region of NFL is moved to the boundary of the superconducting phase, implying that they are probably governed by different mechanisms.
@article{arxiv.1505.00455,
title = {Spin-Fluctuation-Induced Non-Fermi-Liquid Behavior with suppressed superconductivity in LiFe$_{1-x}$Co$_{x}$As},
author = {Y. M. Dai and H. Miao and L. Y. Xing and X. C. Wang and P. S. Wang and H. Xiao and T. Qian and P. Richard and X. G. Qiu and W. Yu and C. Q. Jin and Z. Wang and P. D. Johnson and C. C. Homes and H. Ding},
journal= {arXiv preprint arXiv:1505.00455},
year = {2015}
}