Pressure-dependent resistivity and magnetoresistivity of erbium

Abstract

A comprehensive resistance study of erbium subjected to a hydrostatic pressure is presented. From the experimental results we derive a p-T phase diagram for the magnetic phases in erbium. In the zero-temperature limit, the conical structure is predicted to transform into the cycloidal one at a pressure of about 1.3 kbar. Experimentally, the transition is found to occur between 1 and 3 kbar at 4.5 K. The experimental results are analyzed in terms of a variational calculation of the resistivity using the model developed for erbium from previous experiments. The theory of Elliott and Wedgwood is utilized in the account of the superzone effects. The analysis indicates that the a-axis resistivity is slightly affected by the superzones. In the c-axis case the superzone effects do not simply scale with the magnetization, but also reflect the 20% change of the ordering wave vector. This occurs between T N and T C at ambient pressure, and at 4.5 K when the pressure is increased from 1 to 3 kbar. It is tentatively proposed that the tilted cycloidal structure exists in Er, just above T C at ambient pressure and in the interval between 1.3 and 9 kbar at zero temperature.

Neutron Diffraction Study of the p - T Phase Diagram for Erbium

“…At these energies the absorption cross section is approximately 120 barns. Figure 1a shows the electrical resistivity as a function of pressure at T ¼ 4.5 K (filled circles) previously reported in [4]. The resistivity exhibits a rapid increase between 0.5 and 3.5 kbar, with some suggestion of an intermediate phase.…”

“…Our results from PRISMA demonstrate self-consistency in two experiments, and reveal only a modest change in the wave vector at the transition shown in Figure 1a between 0.5 and 3.5 kbar. The wave vector does not approach the predicted value of Q ¼ 0.286 c* (2=7 c*) in [4] but instead adopts a value of Q ¼ 0.242 AE 0.001 c*. This latter value is equivalent to a commensurate wave vector of 8=33 c*: this structure persists until 4.8 kbar where Q is seen to increase rapidly.…”

“…The resistivity exhibits a rapid increase between 0.5 and 3.5 kbar, with some suggestion of an intermediate phase. The solid line is the predicted resistivity based upon our model [4]. For pressures greater than 3.5 kbar the magnetic structure was predicted to have a wave vector of Q ¼ 2=7 c*.…”

“…Using these strain para-meters, Jensen and Mackintosh [3] predicted that the magnetoelastic energy would cause the cone structure to become unstable when a hydrostatic pressure of approximately 2.5 kbar is applied. We have earlier investigated the form of the p-T phase diagram of erbium using electrical resistivity measurements [4]. In this paper we present, results for the ordering wave vector as function of hydrostatic pressure derived from neutron defraction studies.…”

First-principles study of spin-disorder resistivity of heavy rare-earth metals: Gd–Tm series

“…Single-crystal resistivity measurements have also been performed by other group. [24][25][26][27][28] In the f -d model picture, the assumption that the 4f local moment can be treated as a quantum multiplet with a fixed angular momentum J leads to the SDR being proportional to J(J + 1) in the paramagnetic state (in the Born approximation). The effective scattering potential is, however, provided largely by spin alone.…”