Magnetic excitations and nematic spin correlations of uniaxial-strained KFe0.8Ag1.2Te2

KFe0.8Ag1.2Te2 (KFAT) is structurally similar to the parent compounds of iron-based superconductors (PC-IBS). In addition, it also exhibits simultaneous stripe-type magnetic and structural phase transitions. The similarities in KFAT and PC-IBS suggests the 2×2 Fe clusters already contains the essential physics of the nematic state in PC-IBS in the localized limit, and KFAT is an ideal system to study such physics. Here we propose to study the magnetic excitations of uniaxial-strained KFAT (TS,N ~ 35K) at temperatures below and above TS,N by neutron scattering to (1) understand how magnetic excitations connects to the divergent nematic susceptibility seen in magnetic susceptibility, (2) disentangle contributions of spin waves from different domains in the ordered state (as was done for BaFe2As2), and (3) probe the energy dependence of the anisotropy of the continuum at Q1 and Q2.