Characterization of magnetic properties, including magnetocaloric effect, of RE$_{5}$Pt$_2$In$_4$ (RE = Gd-Tm) compounds

Abstract

The RE$_{5}$Pt$_2$In$_4$ (RE = Gd-Tm) rare earth compounds have been investigated by means of X-ray diffraction (XRD) as well as by DC and AC magnetometric measurements. The compounds crystallize in an orthorhombic crystal structure of the Lu$_{5}$Ni$_2$In$_4$-type (\textit{Pbam} space group, No.~55). With decreasing temperature the intermetallics undergo a transition from para- to ferro-/ferri- (RE~=~Gd, Tb, Ho, Er) or antiferromagnetic state (RE~=~Tm). In case of Dy$_{5}$Pt$_2$In$_4$, the ferromagnetic state is reached through an intermediate antiferromagnetic order present in a limited temperature range. The critical temperatures of magnetic ordering range from 4.1~K (RE~=~Tm) up to 108~K (RE~=~Tb). For the majority of investigated compounds, a cascade of additional magnetic transitions is found below the respective critical temperatures of magnetic ordering. The magnetic moments are found solely on the rare earth atoms, while the moments of the remaining Pt and In atoms are absent or are too small to be detected while accompanied by the strong rare earth's moments. The magnetocaloric (MCE) performance of RE$_{5}$T$_2$In$_4$ (RE~=~Gd-Tm) is found quite good, especially while taking into account the compounds with RE = Ho and Er. Maximum magnetic entropy change ($-\Delta S_M^{max}$) reaches 11.8 (RE~=~Ho) or 11.4~J$\cdot$kg$^{-1}\cdot$K$^{-1}$ (RE~=~Er) under magnetic flux density change of 0-9~T. Under the same conditions, the relative cooling power (RCP) and refrigerant capacity (RC) equal 607 and 495~J$\cdot$kg$^{-1}$ (RE~=~Ho) or 434 and 341~J$\cdot$kg$^{-1}$ (RE~=~Er).