Magnetic structure of HoPd2Si2 redefined on the basis of newneutron diffraction data

Abstract

A new sample of HoPd2Si2 (ThCr2Si2-type structure, space group I4/mmm) hasbeen prepared and investigated. Magnetic susceptibility and magnetization dataindicate antiferromagnetic behaviour below TN = 5.8 K. On the basis of powderneutron diffraction data the magnetic structure of the compound has beenredefined and found to be more complex than reported earlier. In thetemperature region from 20 K to 5 K a short-range magnetic order develops.Between 1.5 K and 5 K a long-range magnetic ordering, that could be describedin an enlarged magnetic unit cell (am = 7a, bm = a and cm = 6c), is observed.A complex magnetic structure of sine-wave modulated type with two propagationvectors and Ho magnetic moments parallel to the b-axis is proposed. Moreover,a new attempt to understand the transition from long- to short-rangemagnetic ordering observed in some rare earth compounds with Pd is made.