Temperature modulation and temperature hysteresis studies of dysprosium

Abstract

Temperature modulation studies of the magnetic susceptibility of polycrystalline dysprosium are compared with measurements of minor loop temperature hysteresis of susceptibility in both the ferromagnetic and the spiral spin antiferromagnetic regions. The effects of temperature hysteresis upon susceptibility in the ferromagnetic and antiferromagnetic regions, and the intermediate region which links them, are examined.Temperaturmodulationsuntersuchungen der magnetischen Suszeptibilitlit von polykristallinem Dysprosium werden mit Messungen der kleineren Temperatur-Hystereseschleifen der Suszeptibilitat sowohl in ferromagnetischen als auch im antiferromagnetischen Spiral-Spin-Bereich verglichen. Die Einfliisse der Temperaturhysterese auf die Suszeptibilitiit im ferromagnetischen und antiferroma.gnetischen Bereich und dem Zwischenbereich, der beide verbindet, werden untersucht.Recently we reported ac susceptibility and transient enhancement (TE) studies of polycrystalline gadolinium [4, 51, dysprosium [6] and of a terbium single crystal [7]. T E measurements, wherein a second ac (or pulsed dc) field is applied a t afrequency differing from the primary, was shown to be a sensitive indicator of the presence of domain wall pinning with the enhanced susceptibility being caused by the freeing of the walls by the second field [5]. For gadolinium, T E studies indicate the nucleation of the ferromagnetic walls a t the Curie temperature, T,, and their presence a t lower t,emperatures. For terbium and dysprosiuni the TE studies indicate not only the presence of ferromagnetic domain walls below T, but also the formation, via an interl) Duntroon, ACT 2600 New South Wales, Australia. z, P. 0. Box 4, Canberra, ACT 2600, Australia.

Low Field Magnetic and Thermal Hysteresis in Antiferromagnetic Dysprosium

“…Nevertheless, the hysteresis in C 33 elastic constant was found to vanish in Dy and Tb-Ho alloy at a temperature of 165 K [22]. The present data on χ are also in full agreement with the results of McKenna et al [9], showing only a minor drop at T VP on the order of only a few percent, inset in Figure 5a. Thus, our study of RVE showing that the thermal hysteresis vanishes at T VP = 166 K [25] does not contradict previous studies.…”

“…The data on χ are in full agreement with previous studies, see e.g., [9,20,23]. χ in the AFM phase is 2-3 orders of magnitude lower than χ , and its contribution to the absolute value can be neglected.…”

“…The origin of thermal hysteresis in antiferromagnetic Dy is a long-standing unresolved issue [9][10][11]15,18,20,22,23,25,33]. One of the most comprehensive studies of thermal hysteresis is that undertaken by McKenna et al [9].…”

“…One of the most comprehensive studies of thermal hysteresis is that undertaken by McKenna et al [9]. Using two different experimental techniques-susceptibility measurements and temperature modulation-they showed that the thermal hysteresis in two independent characteristic parameters vanishes at the same temperature somewhat below 170 K [9].…”

“…The latter is a first order magnetostructural transition, since the high-temperature hexagonal lattice undergoes orthorhombic distortions [4,5]. Rare earth metals and their alloys have been the subject of intense studies [6][7][8][9][10][11][12], in particular, due to the complexity of their temperature-field phase diagrams. Several magnetic structures have been reported in Dy between 90 and 178 K: fan [13][14][15], quasi 2D vortex [16], collinear ferromagnetic [17], vortex [18,19], and angle ferromagnetic [19].…”