We report the results of 151Eu Mössbauer spectroscopy on EuPtSi with a chiral structure belonging to the P213 (#198) space group at zero magnetic field. The paramagnetic single absorption forms a magnetic splitting profile directly below TN = 4.0 K and the spectrum at 3.9 K consists of the sum of the paramagnetic single absorption and the magnetic splitting absorption, which indicates a first-order transition at TN = 4.0 K. The temperature dependence of the effective hyperfine fields Hhf at the Eu nucleus follows a power law of Hhf = H0(1 − T=TN) β with H0 = 25.6 ± 0.4 T and β = 0.16 ± 0.01 indicates a full moment of Eu2+ ions. The relative integral intensity I of the 151Eu Mössbauer spectroscopy for EuPtSi is enhanced using a Debye calculation below T0 ’ 15 K, which indicates the development of magnetic correlations. The line width Γ of the 151Eu Mössbauer spectra increases below TFD (’ 8 K) close to the Weiss temperature θp and shows a sharp peak at TN. The magnetic behavior of EuPtSi can be divided into three magnetic regions: the paramagnetic (PM) phase, the fluctuation-disordered (FD) phase and the antiferromagnetic phase with fluctuation disordering (AF with FD). The magnetic fluctuation is realized around the first-order transition between the paramagnetic and helimagnetic states in EuPtSi.
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