Magnetic ordering of hyperfine-coupled nuclear and4f-electron moments in the clathrate compoundPr3Pd20Ge6

Abstract

Complex ac susceptibility, χ = χ − iχ , measurements of the clathrate compound Pr 3 Pd 20 Ge 6 were performed in static fields up to 10 mT for H [001] and at temperatures down to 500 μK. Praseodymium (Pr) nuclear magnetic moments at the 8c site, where quadrupole moments of 4f electrons order at T Q1 = 250 mK, were found to order antiferromagnetically at 9 mK, as shown by a peak in χ and a substantial increase in thermal relaxation time. The large enhancement factor (1 + K 8c ) obtained by calculation of the hyperfine-enhanced nuclear susceptibility of Pr at the 8c site accounts for the high transition temperature of Pr nuclear magnetic moments and the large χ below 30 mK. From analysis of the crystalline electric field and the mean-field approximation, we conclude that a χ peak at 77 mK can be ascribed to an antiferromagnetic ordering of magnetic moments of 4f electrons at the 4a site. We found that nuclear and f-electron moments order separately on two sublattices in this compound. The temperature and magnetic field dependence of χ and χ between 30 and 60 mK are discussed in terms of dissipation phenomena.

Perturbation on hyperfine-enhancedPr141nuclear spin dynamics associated with antiferroquadrupolar order inPrV2Al20Ito1, Higemoto2, Sakai3 et al. 2015Phys. Rev. B8030View full textAdd to dashboardCite

“…The hyperfine enhancement of 141 Pr nuclear magnetism is a common phenomenon for Γ 1 and Γ 3 CEF ground multiplets without dipolar DOF [8][9][10][11]. This effect arises from the Van Vleck-like admixture of magnetic CEF excited multiplets into the nonmagnetic ground multiplets as a result of strong intra-atomic hyperfine coupling [8].…”