Identifying the critical point of the weakly first-order itinerant magnet DyCo2with complementary magnetization and calorimetric measurements

Abstract

We examine the character of the itinerant magnetic transition of DyCo 2 by different calorimetric methods, thereby separating the heat capacity and latent heat contributions to the entropyallowing direct comparison to other itinerant electron metamagnetic systems. The heat capacity exhibits a large lambda-like peak at the ferrimagnetic ordering phase transition, a signature that is remarkably similar to La(Fe,Si) 13 where it is attributed to giant spin fluctuations. Using calorimetric measurements we also determine the point at which the phase transition ceases to be first order: the critical field, µ 0 H crit = 0.4±0.1 T and T crit = 138.5±0.5 K, and we compare these to values obtained from analysis of magnetization by application of the Shimizu inequality for itinerant electron metamagnetism. Good agreement is found between these independent measurements, thus establishing the phase diagram and critical point with some confidence. In addition we find that the often-used Banerjee criterion may not be suitable for determination of first order behavior in itinerant magnet systems. PACS number(s):

Exotic hysteresis of ferrimagnetic transition in Laves compound TbCo2

“…It meant that the order of the zerofield ferrimagnetic transition is lowered by the magnetic field applied. A similar field effect was observed for the ferrimagnetic transition of DyCo 2 [5]. For this similarity, the field-induced lowering of the order of the ferrimagnetic transition of TbCo 2 was not recognized as a rare phenomenon.…”

“…Cubic Laves compounds of RCo 2 (R = rare earth) have shown useful properties such as large magnetostriction, large magnetoresistance and a sizeable magnetocaloric effect [1][2][3][4]. These properties are closely related to their magnetic transitions, which can be driven by a change of temperature, pressure or magnetic field [5,6]. In their magnetically ordered lattices, 4f moments of light R favor a ferromagnetic coupling with 3d moments of Co, whereas those of heavy R favor an antiferromagnetic coupling [7,8].…”

Direct magnetocaloric characterization and simulation of thermomagnetic cycles

“…This approach could be insightful in describing processes close to the critical point between first and second order behaviors, 60 shown by the most promising materials for applications.…”

Colossal Barocaloric Effect by Large Latent Heat Produced by First‐Order Intersite‐Charge‐Transfer Transition

“…The entropy changes due to the weakened firstorder transitions are corrected with a missing latent heat by assuming that the total amount of released entropy is conserved. [39][40][41] (See the details of corrections in Experimental Section. Alternative analyses including one with the uncorrected data shown in Figure 5a are also given in the Supporting Information.)…”