Electron spin resonance (ESR) and magnetic-susceptibility experiments in the rare-earth-doped (R=Nd, Er, and Yb) cubic semiconducting YBiPt allow estimates of the fourth (Formula presented) and sixth (Formula presented) order crystal-field parameters for this compound. It is found that these parameters are of the same order for all the R studied. On the other hand, no crystal-field effects were found for the (Formula presented) doped single-crystal system. Consistent with the small gap semiconducting character of the YBiPt intermetallic compound, a Dysonian ESR line shape with no g shift and Korringa broadening was observed. © 1999 The American Physical Society.

The pressure induced quantum phase transition of the weakly ferromagnetic metal MnSi is studied using zero-field 29Si NMR spectroscopy and relaxation. Below P(*) approximately 1.2 GPa, the intensity of the signal and the nuclear spin-lattice relaxation are independent of pressure, even though the amplitude of the magnetization drops by 20% from the ambient-pressure amplitude. For P>P(*), the decreasing intensity within the experimentally detectable bandwidth signals the onset of an inhomogeneous phase that persists to the highest pressure measured, P>/=1.75 GPa, which is well beyond the known critical pressure P(c)=1.46 GPa. Implications for the non-Fermi liquid behavior observed for P>P(c) are discussed.

The magnetic properties of the ground state of a low-density free-electron gas in three dimensions have been the subject of theoretical speculation and controversy for seven decades. Not only is this a difficult theoretical problem to solve, it is also a problem which has not hitherto been directly addressed experimentally. Here we report measurements on electron-doped calcium hexaboride (CaB₆) which, we argue, show that-at a density of 7× 1019 electrons cm-3-the ground state is ferromagnetically polarized with a saturation moment of 0.07 µ_B per electron. Surprisingly, the magnetic ordering temperature of this itinerant ferromagnet is 600 K, of the order of the Fermi temperature of the electron gas.