The magnetic properties of single crystals of erbium and some yttrium-erbium and lutetium-erbium alloys between 1.2 and 300°K

Abstract

Carefully analyzed splierical cinclc crystal riamplex wore prepared oL' orbiiiiu and of alloyy whose approximate compositions were: , Y^oEr,;^. Y?Er-^ , LUo-jEr^^, Lu^oEr^o, and. Ma^pietie measureraerits were made on each ol' these samples along the tt'iroc principle crystallographic axes in the range 1.2 to gOO^K and applied fields up to K-Oe. For pure erhiim, the saturation moment along the c-axis was found to be 270.O ±2.0 emu/g. by fitting the data to a plot and extrapolating to 0°K. This is to be compared with a theoretical value of 3OO.5 emu/g. The discrepancy between experiment and theory is apparently the result of a ferromagnetic spiral arrangement of spins where the spins are cocked at an angle to the c-axis rather than being aligned parallel to it. Curie and N^el temperatures were found at l8.2 ±0.5 and 86.5 ±0.5°K respectively. Peaks in the c-axis moment vs. temperature curves were also observed which extrapolated to zero-field temperatures of 28.0 ±0.5 and 50.5 ±0.5°K. The latter corresponds to the transition from one antiferromagnetic structure to another while the significance of the former is unknown. Peaks occurred in both the a-and b-axis moment vs. temperature curves below about 18.5 K-Oe. Below about 10 X-Oe., the temperature of the peaks was field independent and occurred at about l8.2°K. In both the a-and b-axis moment vs. field curves, there were discontinuous increases in moment at about 18.5 K-Oeo near 4.2°K. These apparently correspond to a sudden transition to a nearly parallel alignment of spins at an angle of about 23° to the c-axis. Some very small basal-plane anisotropy was observed below 40°K. At 4.2°X, the b-axis moment was about 2% larger at .high V rie Id:: " None or I,lie alloyt; ;;i,uii.ic:d wore i'crromfinotic in zrjro l'i'tld. 'I'ha l.timprrattircr, of thn alloyri ware proportional to thr: %/% jkw. t oT th'.; _2 avcra}:c do Gennos factor, = AG''\ The constant, A, warj found to bo '19.0 for tlio yttriiun-crbium alloys and 53*5 for the lutetium-erbium alloys. An anomalouiî peak was observed in the c-axis moment vs. temperature curves for two alloys, LuggEr^g and YgoErgg. In both alloys, the peak vfas not observed at fields less than about 6 K-Oe. However, by extrapolating to zero field, the temperatures of the peaks were determined to be 27-5 ±1.0 and 17•5 ±1.0°K respectively for the two alloys. In addition to these • anomalies, a peak was observed at 29.0 ±0.5°K for a polycrystalline YggEryg alloy by a zero-field mutual-induetance bridge technique. These peaks are evidently due to a transition between two different magnetic structures, but whether they correspond to the structure change observed by Child _et in yttrium-erbium alloys is not known. Peaks occurred in both the a-and b-axis moment vs. temperature curves for the YssEr^g, LugsEr^s, YgoErgo, and LUgoErso alloys at l6.4, I6.I, 12.5, and about 9.0°K respectively. These peaks are apparently related to the l8.0°K basal-plane peak in pure erbium. This peak corresponds to the ferromagnetic-antiferromagnetic transition in p...

The low temperature specific heat of some cerium and lanthanum Laves phase compounds

“…The application of a field to a material which has a Neel point causes the Neel point of the material to be lowered (30).…”