Magnetism in RCo_{2} (R = Dy, Ho, Er, Tm) Under Hydrostatic Pressure

Abstract

The short-range parimagnetic congurations, observed in the heavy rare-earth RCo2 compounds in paramagnetic range far above the Curie temperature TC , consist in formation of ferromagnetic cobalt clusters antiferromagnetically coupled to the neighboring R magnetic moments. The characteristic temperature of the onset of parimagnetism T f is very sensitive to changes of external conditions like pressure or composition. The pressure coecients ∂T f /∂p and ∂TC /∂p are comparable, indicating a close connection of underlying mechanisms. Our recent measurements indicate systematic evolution of the pressure coecients with spanning the rare-earth series from Dy through Tm in RCo2 with a specic case TmCo2.

Magnetism in TmCo2

“…We suppose that these discrepancies come from dierent quality of the measured samples. Based on the characterization of our sample by XRD and EDX, we trust in a good quality of our sample showing better purity in comparison with our samples from the RCo 2 family, showing more consistent results with literature [2,6,7]. The position of anomaly denoted by T f is in the agreement with the position of ipping temperature published in [7] obtained from the XMCD measurement.…”

“…The microprobe has shown only tiny impurities of Tm rich phase in the majority of the TmCo 2 phase. We should note that despite more problematic operation with Tm because of its higher vapor pressure, the quality of this Tm-based sample surprisingly appears to be better in comparison to other RCo 2 compounds previously prepared (with R = Er, Ho, Dy [2,6]), where there was visible a small amount of foreign phase.…”

Magnetic and magnetocaloric properties of DyCo2Cx alloys

“…Below TC, the DyCo2 compound is ferrimagnetic. The magnetically polarized Co sublattice orients antiparallelly to the Dy sublattice [30]. The magnetic phase transition temperature of the impurity phase DyCoC is much smaller than that of DyCo2Cx, being 6.8 K as determined from the heat capacity [31] or 8 K from a magnetization measurement [32].…”