The Interplay of Electronic and Nuclear Magnetism in PtFex at Milli-, Micro-, and Nanokelvin Temperatures

Abstract

We have measured ac susceptibility, nuclear magnetic resonance, and nuclear heat capacity of two PtFexsamples with concentrations of magnetic impurities x = 11 ppm and 41 ppm at magnetic fields (0 ± 0.05) mT≤B≤248 mT. The susceptibility data have been measured at temperatures of 0.3 μK≤T≤100 mK, no hint for nuclear magnetic ordering could be detected to a temperature of 0.3 μK. The nuclear heat capacity data taken at 1.4 μK≤T≤10 mK show enhanced values which scale with x at low polarization. This effect is described by a model assuming an internal magnetic field caused by the impurities. No indication for nuclear magnetic ordering could be detected to 1.4 μK. The nuclear magnetic resonance experiments have been performed on these samples at 0.8 μK≤T≤0.5 mK and 2.5 mT≤B≤22.8 mT as well as on three other samples with x = 5, 10, 31 ppm in a different setup at 40 μK≤T≤0.5 mK and at 5.4 mT≤B≤200 mT. Spin-lattice and effective spin-spin relaxation times τ1and τ2* of 195Pt strongly depend on x and on the external magnetic field. No temperature dependence of τ1and τ2*could be detected and the NMR data, too, give no hint for nuclear magnetic ordering to 0.8 μK.