Nuclear Magnetic Ordering in PrCu6

Abstract
We have observed in PrCu6 a sharp peak in the heat capacity and rapid change in the magnetization at 2.5 mK consistent with the occurrence of nuclear magnetic ordering below that temperature. Applying magnetic fields greater than 100 G rounds the transition. The behavior observed is similar to ferromagnetism in electronic systems, but other structures showing weak "ferromagnetism" are not ruled out.