KONDO SCREENING AND MAGNETIC-ORDERING IN FRUSTRATED UNI4B

UNi4B exhibits unusual properties and, in particular, a unique antifer romagnetic arrangement involving only 2/3 of the U sites. Based on the low temperature behavior of this compound, we propose that the remain ing 1/3 U sites are nonmagnetic due to the Kondo effect. We derive a m odel in which the coexistence of magnetic and nonmagnetic U sites is t he consequence of the competition between frustration of the crystallo graphic structure and instability of the 5f moments.