Observation of transitions to spin-slip structures and splitting of the Néel temperature of holmium in magnetic fields

Abstract

We present the results of magnetization measurements on single-crystal holmium using a SQUID magnetometer in the temperature range from 4 to 140 K in magnetic fields up to 5.5 T. In low fields (0.01 T) the magnetization versus temperature data show a spiral to conical transition at Tc=16 K and the Néel temperature at 132 K. In addition, we observe new anomalies in the temperature dependence of the magnetization along the a, b, and c axes at 20, 24, 42, and 98 K. These new anomalies appear at the same temperatures as observed by Bates et al. [J. Phys. C 21, 4125 (1988); 21, 4113 (1988)] in ultrasonic velocity measurements on holmium. These anomalies could be accounted for within the frame work of the ‘‘spin-slip’’ model of Gibbs and co-workers. In the c axis magnetization we observe a splitting of the Néel temperature in magnetic fields greater than 0.5 T. The H-T phase diagrams of the magnetic phases of holmium for fields in three directions (along the a, b, and c axes) are presented.

Correlations between stacked structures and weak itinerant magnetic properties of La2−xYxNi7compounds

“…This reveals a complex magnetic behavior of La 2 Ni 7 which origin has still to be solved. The co-existence of different AFM ordering temperatures can be due for example to a complex helimagnetic structure with propagation vectors along the different crystallographic axis as it has been observed for holmium-based compounds [50][51][52].…”

Theory of commensurable magnetic structures in holmium

“…The possibility that the magnetic structure may lock into commensurable values at elevated temperatures was investigated at Chalk River by Tindall, Steinitz and collaborators. [14][15][16][17][18][19][20][21][22][23][24] They monitored the position of the fundamental magnetic diffraction peak as a function of temperature at fields applied along the c-direction or along the bdirection, and they found several plateaus in the temperature variation of τ . In the presence of a c-axis field of 30 kOe the (221)-and the (211)-structures were found to be stable around 42 K and 96 K, respectively, in both cases within a temperature interval of 2-3 K. In a b-axis field of 14 or 30 kOe the (211)-structure is again stable for a couple of degrees, which was also observed to be the case for the (21)-structure, τ = 2/9, at about 75 K. Finally, they observed τ to stay close to the value 5/18 between 126 K and the Néel temperature, when applying a field of 30 kOe along the b-axis.…”

A model for the occurrence of lock-ins in holmium in c-axis magnetic fields

“…In a sequence of papers [9] [19] [20] [21] [22] [28], lockins were reported at 1/5, 2/9, 1/4, and 5/18 in addition to the lock-in at 1/6 at T C which occurs even in zero field, and one found by Gibbs et al [6] at 2/11. A comparison of the field and temperature values where lock-ins occur with the phase boundaries on a phase diagram [8] obtained from magnetization measurements, shows a clear correspondence. We have also reported the observation of anomalous "noise", presumably due to fluctuations, in dilatometric measurements [23].…”