Ferromagnetism in structurally disordered UFe0.39Ge2

New Insights into the Crystal Structure of Ute0.25ge2 = U4tge8 (Te = Ru, Os) and Ferromagnetic Properties of the Os-Bearing Uranium Germanide

“…As seen, the values of Θ D obtained in the low-temperature range are consistent with those obtained in the high-temperature range. The Debye temperature is close to the values reported for the other UTE1-xGe2 compounds [17,22,24] and has a magnitude characteristic of intermetallic compounds. The Sommerfeld coefficient obtained at low T is moderately enhanced and close to its values found in UNi1-xGe2 (about 54 mJ K -2 molU -1 [22]), in URu1-xGe2 (about 61 mJ K -2 molU -1 [24]) and in UFe1-xGe2 (about 123 mJ K -2 mol −1 [17]).…”

“…The Debye temperature is close to the values reported for the other UTE1-xGe2 compounds [17,22,24] and has a magnitude characteristic of intermetallic compounds. The Sommerfeld coefficient obtained at low T is moderately enhanced and close to its values found in UNi1-xGe2 (about 54 mJ K -2 molU -1 [22]), in URu1-xGe2 (about 61 mJ K -2 molU -1 [24]) and in UFe1-xGe2 (about 123 mJ K -2 mol −1 [17]). For the sake of comparison, it is worth recalling here that the value of the Sommerfeld coefficient determined for the structurally-related UGe2 is equal to 34 mJ K -2 mol -1 [16], which is about two or four times smaller than that obtained for the ternary germanides.…”

“…An upturn of the electrical resistivity at the lowest measured temperatures clearly demonstrates the absence of superconductivity in the UTE1-xGe2 series [17,22,24], at least at ambient pressure. It has been suggested that this upturn is due to the crystallographic disorder induced by the partly occupied transition metal site.…”

“…The recently reported UTE1-xGe2 family crystallizes in the orthorhombic (TE = Fe [17,18], Co [19], Ni [20][21][22][23]) or slightly monoclinically distorted (TE = Ru [24]) CeNiSi2 structure-type strongly related to that of UGe2 [24]. In particular, in these structure-types, U-atoms form almost identical zigzag chains resulting from the formation of almost identical layers of Ge-centered [U6] trigonal prisms separated by planar layers of Ge-atoms, without (in UGe2) or with (in UTE1-xGe2) partial intercalation of the transition element TE on either side of this planar layer.…”

Competition of Magnetocrystalline Anisotropy of Uranium Layers and Zig-Zag Chains in UNi$_{0.34}$Ge$_2$ Single Crystals

“…The compounds UTE 1−x Ge 2 (where TE stands for a transition metal) are another, relatively recently discovered and described in the literature, family of uranium germanides. They crystallize in the orthorhombic CeNiSi 2 structure type (in the case of the phases with TE = Fe [15][16][17], Co [18], and Ni [19][20][21]), or a slightly monoclinically distorted derivative (for TE = Ru [22] and Os [23]). A common feature of the compounds UTE 1−x Ge 2 and the ferromagnetic superconductors UGe 2 , URhGe, and UCoGe is the presence of parallel uranium zig-zag chains.…”