DISCOVERY OF NOVEL MAGNETIC FEATURES IN THE HEAVY-ELECTRON COMPOUND U2ZN17

Transverse field mu+ SR-measurements on a single crystal sample of U2Zn17 reveal a strikingly non uniform magnetic behavior. While part (approximately 30%) of the U-5f moments remain paramagnetic below T(N) = 9.7 K (at least for external fields greater-than-or-equal-to 0.2 T) another part (approximately 20%) enters into a complex order below 9.7 K which is associated with huge internal field spreads at the mu+ sites. Above T(N) this part causes an anisotropic mu+ Knight shift involving direction cosines up to 8th order. Only the remaining fraction is compatible with the simple AF order suggested by neutron diffraction studies.