Reducing extrinsic hysteresis in first-order La(Fe,Co,Si)13 magnetocaloric systems

Abstract

Citation: MOORE, J.D. ... et al, 2009. Reducing extrinsic hysteresis in firstorder la (Fe,Co,Si)13 magnetocaloric systems. Applied Physics Letters, 95 (25)

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

“…As expected, there is no shift in the critical field, H c , nor decrease in the hysteresis, ΔH, in contrast to other systems where compositional inhomogeneities, poor thermal conductivity and/or strong magneto-structural coupling (strain relief) play a role. 25,39 As such, it seems our estimates of T crit and H crit are valid for both bulk and fragmented samples. Also shown in figure (5b) is the trajectory of the peak in C p measured by ac calorimetry, C peak .…”

“…Slower field sweep rates close to T c (where the field hysteresis, H c ↑ -H c ↓ , is larger), confirmed that any hysteresis seen was intrinsic to the material system, and not a result of non-isothermal conditions due to the magnetocaloric effect itself. 25 The magnetic data were corrected for demagnetization effects with a demagnetization factor, N=0.33.…”

Large entropy change accompanying two successive magnetic phase transitions in TbMn2Si2 for magnetic refrigeration

“…A number of magnetic materials with large values of DS M /DT ad accompanied by a first order phase transition have been reported. [9][10][11][12][13][14][15] Nevertheless, only some of them, especially rare-earth-based intermetallic compounds, [16][17][18][19][20][21] have a small hysteresis loss, which is desirable for practical application. In addition, large reversible MCEs only appear in a small temperature range for most of the rare-earth-based intermetallic compounds.…”

Origin of Hysteresis in La0.67Ca0.33MnO3

“…In this case the hysteresis has been shown to have a clear magnetic field sweep rate dependence that is controlled by the sample size [6]. As well as this, the well known superheating and supercooling scenario, where depending on the cooling (heating) rate the system can remain in the higher energy state and overshoot the transition, only dropping to a lower energy state at a lower (higher) temperature or field, can also create an artificial hysteresis with a magnitude dependent on cooling (or heating) rate [17].…”

“…La(Fe 1-x-y Co y Si x ) 13 H is rather unique because it clearly shows a first order, field driven metamagnetic transition and yet the intrinsic hysteresis is small. Nevertheless extrinsic sources of hysteresis in this system can be significant, due in part to the large latent heat, large heat capacity and poor thermal conductivity at the metamagnetic transition, as discussed elsewhere [6].…”