| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1600949 | Intermetallics | 2011 | 6 Pages |
The novel R3CoGe2 compounds adopt the La3NiGe2-type structure (space group Pnma) with the following cell parameters: a = 1.1706(1), b = 0.42267(5), c = 1.1242(1) nm for Sm3CoGe2; a = 1.15845(5), b = 0.41905(2), c = 1.12088(5) nm for Gd3CoGe2; a = 1.14942(4), b = 0.41705(2), c = 1.11030(4) nm for Tb3CoGe2 and a = 1.1431(2), b = 0.41500(5), c = 1.1040(2) nm for Dy3CoGe2. The R3CoGe2 compounds undergo a ferrimagnetic type ordering (TCN = 150 K for Gd3CoGe2). Neutron diffraction studies show that Pr3CoGe2 and Nd3CoGe2 have a commensurate ferromagnetic component along the a axis and a commensurate antiferromagnetic component along the c axis (Pn’ma magnetic space group): (MPrF)a = 2.59(9) μB, (MPrAF)c = 1.58(4) μB, ∣MPr∣ = 3.03(9) μB for Pr3CoGe2 and (MNdF)a = 2.6(1) μB, (MNdAF)c = 1.65(6) μB, ∣MNd∣ = 3.1(1) μB for Nd3CoGe2 at 2 K.Magnetocaloric effect of Gd3CoGe2 in terms of the isotherm entropy change, ΔSiso, was derived from the magnetization measurement, and it reaches the maximum value of ΔSiso = −4.9 J/kg•K in the 139–144 K temperature range.
Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideResearch highlights► The X-ray diffraction patterns of present {Sm, Gd, Tb, Dy}3CoGe2 showed that they adopt the La3NiGe2 (Gd3NiSi2)-type structure. ► The magnetic transition temperatures in Gd3CoGe2 and Tb3CoGe2 follows the de Gennes rule, whereas Ce3CoGe2, Pr3CoGe2 and Nd3CoGe2 do not follows the de Gennes rule. ► The magnetocaloric effect for Gd3CoGe2 in terms of the isothermal entropy change, −ΔS, reaches the maximum value of 4.9 J/kg⋅K in the 139–144 K temperature region. The maximum |ΔS| value is lower than those observed for isostructural Gd3NiGe2 and Gd3NiSi2. ► Pr3CoGe2 and Nd3CoGe2 has same commensurate ferrimagnetic type ac ordering with the magnetic point group m’mm = {1, mY, mZ, 2X} + {1¯, mX, 2Y, 2Z} × 1’ and the magnetic space group Pn’ma.
