LAUSR

The magnetic structure of NdPd5Al2 has been studied by neutron powder diffraction. We observed the magnetic reflections with the modulation vector \(q = (1/2,0,0)\) below the ordering temperature TN. We found a collinear magnetic structure with a Nd moment of 2.7(3) μB at 0.5 K parallel to the c-axis, where the ferromagnetically ordered a-planes stack with a four-Nd-layer period having a ++−− sequence along the a-direction with the distance between adjacent Nd layers equal to a/2 (magnetic space group Panma). This “stripe”-like modulation is very similar to that in CePd5Al2 with \(q = (0.235,0.235,0)\) with the Ce moment parallel to the c-axis. These structures with in-plane modulation are a consequence of the two-dimensional nature of the Fermi surface topology in this family, originating from the unique crystal structure with a very long tetragonal unit cell and a large distance of >7 A between the rare-earth layers separated by two Pd and one Al layers.