Measurement of pressure effects on the magnetic and the magnetocaloric properties of the intermetallic compounds DyCo₂and Er(Co_1−xSi_x)₂

Abstract

The effect of external pressure on the magnetic properties and magnetocaloric effect of R(Co 1-x Si x ) 2 [R= Er, Dy and x=0, 0.025 and 0.05] compounds has been studied. The ordering temperatures of both the parent as well as the Si substituted compounds are found to decrease with pressure. In all the compounds, the critical field for metamagnetic transition increases with pressure. It is seen that the magnetocaloric effect in the parent compounds is almost insensitive to pressure, while there is considerable enhancement in the case of Si substituted compounds. Spin fluctuations arising due to the magnetovolume effect play a crucial role in determining the pressure dependence of magnetocaloric effect in these compounds. Analysis of the magnetization data using the Landau theory has shown that the magnitude of the Landau coefficient (C 3 ) decreases with Si concentration whereas it is found to increase with pressure. The isothermal magnetic entropy change is found to behave in the same manner as C 3 , both with Si concentration (at ambient pressure) as well as with the applied pressure.

Magnetocaloric and magnetotransport properties ofR2Ni2Sncompounds (R=Ce, Nd, Sm, G

“…Compounds showing field-induced magnetic transitions and/or structural transitions have been found to exhibit very large MCE, as in the case of Gd 5 Si 2 Ge 2 . [9][10][11] Giant magnetocaloric effect was also found in LaFe 11.4 Si 1.6 , 12 MnAs, 13,14 FePMnAs, 15 RCo 2 , 16,17 Heusler alloys, 18 manganites, 19 etc. In most of these cases, the giant MCE is a result of a first-order ferromagnetic ͑FM͒ to paramagnetic transition.…”

Theoretical aspects of the magnetocaloric effect

“…It has been experimentally shown that the magnetocaloric potentials ∆S iso and ∆T ad in ErCo 2 , HoCo 2 and DyCo 2 exhibit a jump around the magnetic ordering temperature, due to the first order magnetic phase transition [250][251][252][253][254][255][256][257][258][259][260][261][262][263]. In the other compounds of the RCo 2 series the phase transition is of second order and the magnetocaloric potentials exhibit the usual behavior.…”

The effect of boron doping on crystal structure, magnetic properties and magnetocaloric effect of DyCo2

“…6 Moreover, the study of the pressure effects on DyCo2 reveals that the Curie temperature decreases with the application of external pressure due to the contraction of the lattice parameter. 22 Doping by interstitial elements (H, C, and B) usually leads to an increase of the lattice constant, and the H absorption has been successfully applied to adjust the Curie temperature of La(Fe0.89Si0.11)13 from 190 K to room-temperature, while preserving the first-order of the magnetic transition. 15 However, the hydrogenation treatment for DyCo2 leads to disproportionation and amorphization of the compound.…”