We describe a novel capacitance dilatometer, which is simple to construct, compact in size, and which can be used with samples of any shape, size, conductivity, or dielectric constant.

We report measurements of the intensity and position of the satellites arising from the helimagnetic structure of holmium in magnetic fields applied along different crystal axes, concentrating on lock-in effects at commensurate values of the spiral wave vector τ. We have made the first observations of the lock-in at τ=1/5 near 42 K in a 3 T c-axis field as well as the lock-in at τ=1/4 in a 3 T b-axis field. We have also observed a lock-in at τ=5/18 in a b-axis field near the Néel temperature of 132 K, in contrast to an earlier reported value of 8/29. This illustrates the origin of the splitting previously reported by us in magnetization and dilatometric measurements.

No abstract

No 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.