Magnetism in TmCo₂

Abstract

Recently a new wave of interest in physics of RCo2 compounds has been boosted by reports on unusual magnetic short range order congurations in the heavy rare-earth RCo2 ferrimagnets in paramagnetic state. The newly observed phenomenon called parimagnetism consists in a short-range antiferromagnetic coupling between small ferromagnetic Co clusters and the nearest rare-earth moments. This paper is devoted to results of our experimental investigation of carefully prepared and characterized samples of TmCo2, a compound on which controversial results can be found in literature. Detailed magnetization, AC susceptibility, specic heat and electrical resistivity measurements revealed two magnetic phase transitions at 4.6 and 3.6 K, respectively. The anomalies connected with the transitions are strongly dependent on magnetic eld and hydrostatic pressure. The AC susceptibility anomaly connected with the onset of parimagnetism has been found at T f = 35 K. Contrary to other heavy rare-earth RCo2 counterparts T f of TmCo2 is entirely pressure independent.

Lattice distortion in TmCo2: A poly- and single-crystal study

“…It is in agreement with the discovered magnetic easy axis, because the change of the structure type is related to the magnetic ordering and the easy axis direction affects the type of the distortion [5,10,27]. Also the observed structural distortion confirms the existence of the first order phase transition, which was detected in the previous resistivity and heat capacity measurements [21]. The first order type of transition is evident in our data by the sudden change of the crystal structure (Fig.…”

“…The results of the LT-XRD on the poly-crystalline TmCo 2 (Fig. 1) correspond well with the previous measurement of the electric resistivity, heat capacity and AC magnetic susceptibility performed on this sample [21]. The structural transition is strictly described by the sudden splitting of specific reflections in the XRD patterns (Fig.…”

“…Preparation and characterization of these samples was reported in Ref. [21]. In addition a single-crystalline sample was studied.…”