Calibration of ac and dc magnetometers with a Dy2O3 standard

Abstract

The ac susceptibility and magnetization curves of a glued Dy 2 O 3 powder sample are measured by an ac susceptometer and a dc superconducting quantum interference device magnetometer, both of which have been calibrated previously. It is shown that the magnetic moment of the paramagnetic sample as a function of field and temperature may be accurately expressed by a combination of the Curie-Weiss law and the Langevin function at T > 45 K with three adjusting parameters, so that the dc magnetization curves and the magnitude and phase of ac susceptibility at different values of dc bias field measured by any magnetometer can be calibrated by using Dy 2 O 3 as a standard. The expressions are empirical and cannot be justified in the entire field and temperature range by existing theories of paramagnetism. Below 10 K, indication of approaching a possible phase transition is found. It is shown that pure Dy 2 O 3 powder may be used as a primary standard, with susceptibility [13.28(T + 17)] −1 emu/Oe/g at T > 50 K and H < 10 kOe, in consistency with the Curie-Weiss law and the quantum mechanical theory of paramagnetism.

A flux extraction device to measure the magnetic moment of large samples; application to bulk superconductors

“…Calibration procedures usually make use of standard samples 17,28 made of Ni, MnF 2 , Pd, or, more recently, Dy 2 O 3 . They rely on the well-known magnetic susceptibility of such materials and their associated well-defined magnetization in an externally applied magnetic field.…”

“…16,25,26 However, fundamental to this technique is the assumption of a homogeneous sample magnetization and an increased complexity of the coil arrangement, which impedes its practical application for large samples. Simpler alternatives have been also considered, including (i) the modification of a calibration constant by assuming a specific sample shape and a homogeneous magnetization 17,27,28 and (ii) the use of deconvolution techniques to determine the magnetization distribution of extended samples along their major geometrical axis. 29,30 Unfortunately, these methods are not applicable to the measurement of bulk superconducting magnets because (i) the assumption of a homogeneous magnetization state does not hold and (ii) they cannot be described as extended samples given that their radius can be comparable with their height.…”

Magnetic properties of Dy nano-islands on graphene

“…2 shows the XAS at the Dy M 4 and M 5 edges for the two circularly polarized X-ray beams at T = 15 K and B = 5 T for the thin and thick samples ( Fig. 1) and for Dy 2 O 3 , for comparison (Dy 2 O 3 is paramagnetic to low temperature [22]). The difference between the two circularly polarized XAS (µ + and µ − ) shows two prominent XMCD signals.…”

Dysprosium oxide and dysprosium-oxide-doped titanium oxide thin films grown by atomic layer deposition

“…Dysprosium and dysprosium oxide have been materials of interest for a long time [1][2][3][4][5][6][7][8][9] as dysprosium is a lanthanide metal with the largest magnetic moment and susceptibility. 2 In addition, combination of polymeric architectures with dysprosium ions can produce hybrid materials with extremely rich properties.…”

“…Dysprosium oxide has been considered as a candidate of high-permittivity (high-k) capacitor dielectric for nonvolatile memory applications 3 and as a high-k gate dielectric. [4][5][6] Regarding the performance of Dy 2 O 3 as essentially a paramagnetic oxide, standards in the form of Dy 2 O 3 powders have been exploited for quantum interference magnetometer, 7 vibrating sample magnetometer (VSM), 8 or in the form of small single crystals as additive seeds for superconducting materials for a susceptometer. 9 Dysprosium-doped polymers and glasses can emit white light, 10,11 while Dy:PbGa 2 S 4 compound has been shown to be a solid state laser material emitting at 4.32 lm when pumped by 1.7 lm laser diodes.…”