Eur. Phys. J. B 43, 163-174 (2005)
https://doi.org/10.1140/epjb/e2005-00039-1

Uncompensated antiferromagnetic structure of Ho₂Ni₂Pb

¹ Hahn-Meitner-Institute, SF-2, Glienicker Str. 100, 141 09 Berlin, Germany
² Advanced Materials Department, IPICyT, Apartado Postal 3-74,Tangamanga, 78231 San Luis Potosi, SLP, Mexico
³ Materials Research Laboratory, John F. Welch Technology Center, Bangalore - 560 066, India
⁴ Kamerlingh Onnes Laboratory, Leiden University, 2300 RA Leiden, The Netherlands and Max-Planck-Institute for Chemical Physics of Solids, 01187 Dresden, Germany

Corresponding author: ^a prokes@hmi.de

Received: 6 July 2004
Revised: 6 December 2004
Published online: 25 February 2005

Abstract

We have studied the magnetic structure of the orthorhombic compound Ho₂Ni₂Pb by means of neutron diffraction in zero field and in magnetic fields up to 4.5 T. Both powder and single-crystalline samples were used. Previous bulk measurements suggest two distinct magnetic phase transitions: one at T_N = 7.0 K and the other at 4.8 K. Our neutron diffraction measurements, which were made in the range 1.5-20 K, showed that Ho₂Ni₂Pb has a collinear magnetic structure with unequal number of up and down Ho moments that are aligned parallel and antiparallel to the c axis. At the lowest temperatures the Ho moments are equal in size, each 8.3  in agreement with magnetization data. The magnetic structure can be described as having a  magnetic unit cell. Below T_s = 3.0 K the structure is squared up. A smooth development of all the magnetic moment magnitudes indicates that the magnetic structure remains in principle the same over the whole temperature range, the “phase transition” around 4.8 K can be identified as an inflection point in the temperature dependence of one of the Ho moments. With increasing temperature there is a clear development towards a simple transverse sine-wave modulated magnetic structure that is established just below T_N.