Antiferromagnetism of RPtX (R = Ho, Er; X = Si, Ge) compounds

Abstract

X-ray and neutron diffraction as well as magnetometric measurements performed for HoPtX and ErPtX (X = Si, Ge) compounds indicate that they are crystalline and that they have the orthorhombic TiNiSi-type crystal structure. They are antiferromagnetic at low temperatures. A collinear magnetic structure with the propagation vector k = |1/2,0,1/2|, stable between 1.5 K and the Néel point at 3.1 K is observed in HoPtSi. HoPtGe is paramagnetic at 1.8 K. A collinear magnetic order described by the wavevector k1 = |0,1/2,0| has been found in ErPtSi and ErPtGe. As the temperature rises this structure transforms in both compounds into a sine modulated one with the wavevector k2 = |0,ky,0|. The Néel points of ErPtSi and ErPtGe are 4.0 and 4.1 K respectively.