Electron Spin Resonance of Eu on triangular layers in EuT2P2 (T =Mn, Zn, Cd)

We report on the electron spin resonance (ESR) of Eu${}^{2+}$ in Eu$T_2$P${}_2$ ($T$=Mn, Zn, Cd) single crystals. The temperature dependencies of ESR linewidth and resonance shift show a similar behaviour when approaching the Eu-ordered state – a divergence towards $T_{\mathrm{N}}$, indicating the growing importance of magnetic correlations and the build-up of internal magnetic fields. For $T$=Mn an additional temperature scale of $\approx 47$~K has considerable impact on linewidth, resonance field and intensity. This points to the presence of Mn magnetic correlations which yet were not reported.