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At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Europium c -axis ferromagnetism in Eu ( Co 1 - x Ni x ) 2 - y As 2 : A single-crystal neutron diffraction study

Here we report neutron diffraction results for the body-centered-tetragonal series Eu⁢(Co 1-x ⁢Ni x ) 2-y As 2 , x=0.10, 0.20, 0.42, and 0.82, y≤0.10, that detail changes to the magnetic ordering with nominal hole doping. We report the antiferromagnetic (AFM) propagation vectors, magnetic transition temperatures, and the ordered magnetic moments. We find a nonmonotonic change of the AFM propagation vector with x, with a minimum occurring at the tetragonal to collapsed-tetragonal phase crossover. For x=0.10 and 0.82 we find c-axis helix ordering of the Eu magnetic moments (spins) similar to x=0 and 1, with the spins oriented within the ab-plane. For x=0.20 and 0.42 we find higher-temperature c-axis ferromagnetic (FM) order and lower-temperature c-axis cone order. Using the extinction conditions for the space group, we discovered that the Eu spins are ordered in the higher-temperature c-axis FM phase for intermediate values of x, contrary to a previous report suggesting only Co/Ni spin ordering. Although we cannot directly confirm that the Co/Ni spins are also ordered, we suggest that c-axis itinerant-FM ordering of the Co/Ni spins could provide a molecular field that drives FM ordering of the Eu spins, which in turn provides the anisotropy for the lower-temperature c-axis cone order.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2023

Crystal growth and magnetic structure of ternary silicide Eu Pd 3 Si 2

The hexagonal CaCu 5 –type structure (P6/mmm) is the prototype for more than 100 ternary borides, gallides, and silicides, with general stoichiometry of RTM 3 X 2 (R=lanthanide/alkaline earth; TM=transition metal; X=B, Ga, Si, Ge). Here we report the synthesis, crystal structure, and bulk magnetic properties of polycrystalline and single crystal samples of EuPd 3 Si 2 and its nonmagnetic analog SrPd 3 Si 2 . Both compounds crystallize in the orthorhombic space group symmetry Imma (no. 74, Z = 2, oI12) displaying pseudohexagonal symmetry. Ferromagnetic (FM) order of Eu 2+ at T C1 =78K and a spin-reorientation transition at T C2 =5K appear as distinctive features in bulk magnetization, specific heat, and resistivity/resistance measurements. Neutron powder diffraction measurements on EuPd 3 Si 2 confirm FM order of the Eu 2+ spins below T C1 , with the spins aligned along the a axis below T C2 . Electronic band structure calculations corroborate the crystal structure and the FM state for EuPd 3 Si 2 , with a Pd d–band polarization in the same direction as the Eu 4f polarization, enhancing the observed spin moment.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Physical properties of intergrowth compound Eu 2 CuZn 2 P 3

Here, the physical properties of single-crystalline Eu 2 ⁢CuZn 2 ⁢P 3 were inspected via thermodynamic, transport, and neutron diffraction measurements. Eu 2 ⁢ CuZn 2⁢ P 3 is composed of EuCuP and EuZn 2 ⁢ P 2 motifs stacked in a one-to-one ratio. The magnetic response of Eu 2 ⁢ CuZn 2 ⁢ P 3 is similar to that of EuZn 2 ⁢ P 2 in its A-type antiferromagnetic (semiconducting) state. A Néel temperature of T N = 40.3K is obtained from the specific heat capacity. Single-crystal neutron diffraction reveals a (001) magnetic propagation vector, with primarily in-plane moments coupled along [001] in an up-up-down-down pattern. This spin structure retains the ferromagnetic EuCuP motifs and antiferromagnetic coupling across the EuZn 2 ⁢P 2 motifs. The electrical resistivity is characterized by metallic behavior above 100 K, an increase in ρ upon cooling below ≈ 75K, and a large negative magnetoresistance below T N . First principles calculations evidence a narrow band gap for antiferromagnetic ordering and semimetallic behavior for the ferromagnetic state. This is consistent with the observed effect of magnetic field on the electrical resistivity. Hall effect measurements reveal a field-induced, negative anomalous Hall effect that increases on cooling down to 2 K. Also, an unconventional contribution to the Hall effect dominates the low-field Hall signal, particularly near T N , and is similar in appearance to a topological Hall effect. However, further work is necessary to understand if any of the transport properties have topological origins or if magnetism-induced modifications to the Fermi surface induce these unusual Hall effect signals in this and related materials.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Unconventional magnetotransport and antiferromagnetic order in Eu 2 ⁢InTe 5

Here, we report on the structural characterization and physical properties of Eu 2 ⁢InTe 5 , a distorted square-net motif antiferromagnetic semiconductor. Single crystal x-ray diffraction measurements reveal a distortion of the Te square-net layers such that an orthorhombic supercell is necessary to accurately describe the structure. Magnetization, resistivity, and specific heat measurements confirm antiferromagnetic ordering at 𝑇 𝑁 = 7.3K. Anisotropy in magnetization data suggests the magnetic moments are oriented parallel to the 𝑐 axis. We observe an unconventional transverse magnetoresistance and Hall resistivity in the paramagnetic state (𝑇 ≤ 80K), indicating strong coupling between localized Eu 2+ magnetic moments and conduction electrons. Resistivity and Hall measurements indicate the material is a heavily doped semiconductor, with impurity states related to disorder. Our findings highlight a relatively unexplored Eu-based antiferromagnetic semiconductor with unconventional magnetotransport behavior.

Cook, Matthew S. [Oak Ridge National Laboratory (O↗
DOE OSTI2020

Materials Data on Eu(Cu2As)2 by Materials Project

Eu(Cu2As)2 crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Eu2+ is bonded to six equivalent As3- atoms to form edge-sharing EuAs6 octahedra. All Eu–As bond lengths are 3.04 Å. There are two inequivalent Cu1+ sites. In the first Cu1+ site, Cu1+ is bonded in a distorted trigonal non-coplanar geometry to three equivalent As3- atoms. All Cu–As bond lengths are 2.47 Å. In the second Cu1+ site, Cu1+ is bonded in a distorted single-bond geometry to four equivalent As3- atoms. There are one shorter (2.45 Å) and three longer (2.83 Å) Cu–As bond lengths. As3- is bonded in a 10-coordinate geometry to three equivalent Eu2+ and seven Cu1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Eu(POs)2 by Materials Project

Eu(OsP)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Eu2+ is bonded in a 8-coordinate geometry to eight equivalent Os2- atoms. All Eu–Os bond lengths are 3.38 Å. Os2- is bonded in a 12-coordinate geometry to four equivalent Eu2+ and four equivalent P1+ atoms. All Os–P bond lengths are 2.34 Å. P1+ is bonded in a 4-coordinate geometry to four equivalent Os2- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Eu(SiAu)2 by Materials Project

Eu(AuSi)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Eu2+ is bonded in a 8-coordinate geometry to eight equivalent Au1- atoms. All Eu–Au bond lengths are 3.37 Å. Au1- is bonded to four equivalent Eu2+ and four equivalent Si atoms to form a mixture of distorted edge, face, and corner-sharing AuEu4Si4 tetrahedra. All Au–Si bond lengths are 2.59 Å. Si is bonded in a 5-coordinate geometry to four equivalent Au1- and one Si atom. The Si–Si bond length is 2.35 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Eu(Ni5P3)2 by Materials Project

Eu(Ni5P3)2 crystallizes in the orthorhombic Cmce space group. The structure is three-dimensional. Eu2+ is bonded in a 12-coordinate geometry to eight P3- atoms. There are a spread of Eu–P bond distances ranging from 3.19–3.56 Å. There are four inequivalent Ni+1.60+ sites. In the first Ni+1.60+ site, Ni+1.60+ is bonded in a distorted rectangular see-saw-like geometry to four P3- atoms. There are a spread of Ni–P bond distances ranging from 2.32–2.48 Å. In the second Ni+1.60+ site, Ni+1.60+ is bonded to four P3- atoms to form a mixture of distorted edge and corner-sharing NiP4 tetrahedra. There are two shorter (2.24 Å) and two longer (2.34 Å) Ni–P bond lengths. In the third Ni+1.60+ site, Ni+1.60+ is bonded to four P3- atoms to form a mixture of edge and corner-sharing NiP4 tetrahedra. There are a spread of Ni–P bond distances ranging from 2.16–2.29 Å. In the fourth Ni+1.60+ site, Ni+1.60+ is bonded to four P3- atoms to form a mixture of edge and corner-sharing NiP4 tetrahedra. There are a spread of Ni–P bond distances ranging from 2.19–2.33 Å. There are three inequivalent P3- sites. In the first P3- site, P3- is bonded in a 6-coordinate geometry to two equivalent Eu2+ and six Ni+1.60+ atoms. In the second P3- site, P3- is bonded in a 6-coordinate geometry to one Eu2+ and six Ni+1.60+ atoms. In the third P3- site, P3- is bonded in a 8-coordinate geometry to one Eu2+ and eight Ni+1.60+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Eu(BO2)3 by Materials Project

Eu(BO2)3 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Eu3+ is bonded in a 2-coordinate geometry to ten O2- atoms. There are a spread of Eu–O bond distances ranging from 2.38–2.89 Å. There are two inequivalent B3+ sites. In the first B3+ site, B3+ is bonded in a tetrahedral geometry to four O2- atoms. There is two shorter (1.46 Å) and two longer (1.49 Å) B–O bond length. In the second B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of B–O bond distances ranging from 1.34–1.41 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two equivalent Eu3+ and two B3+ atoms. In the second O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent Eu3+ and one B3+ atom. In the third O2- site, O2- is bonded in a 2-coordinate geometry to one Eu3+ and two B3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Eu(PRu)2 by Materials Project

Eu(RuP)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Eu2+ is bonded in a body-centered cubic geometry to eight equivalent P3- atoms. All Eu–P bond lengths are 3.26 Å. Ru2+ is bonded to four equivalent P3- atoms to form a mixture of edge and corner-sharing RuP4 tetrahedra. All Ru–P bond lengths are 2.33 Å. P3- is bonded in a 8-coordinate geometry to four equivalent Eu2+ and four equivalent Ru2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Eu(LuS2)2 by Materials Project

Eu(LuS2)2 crystallizes in the tetragonal I-42d space group. The structure is three-dimensional. Lu3+ is bonded in a 8-coordinate geometry to eight equivalent S2- atoms. There are a spread of Lu–S bond distances ranging from 2.68–3.10 Å. Eu2+ is bonded in a 8-coordinate geometry to eight equivalent S2- atoms. There are four shorter (2.84 Å) and four longer (3.06 Å) Eu–S bond lengths. S2- is bonded in a 6-coordinate geometry to four equivalent Lu3+ and two equivalent Eu2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Eu(YS2)2 by Materials Project

Eu(YS2)2 crystallizes in the tetragonal I-42d space group. The structure is three-dimensional. Eu2+ is bonded to eight equivalent S2- atoms to form distorted edge-sharing EuS8 hexagonal bipyramids. There are four shorter (2.87 Å) and four longer (3.07 Å) Eu–S bond lengths. Y3+ is bonded in a 8-coordinate geometry to eight equivalent S2- atoms. There are a spread of Y–S bond distances ranging from 2.75–3.07 Å. S2- is bonded in a 6-coordinate geometry to two equivalent Eu2+ and four equivalent Y3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Eu(CuSb)2 by Materials Project

Eu(CuSb)2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Eu3+ is bonded in a 8-coordinate geometry to eight Sb3- atoms. There are four shorter (3.41 Å) and four longer (3.64 Å) Eu–Sb bond lengths. There are two inequivalent Cu+1.50+ sites. In the first Cu+1.50+ site, Cu+1.50+ is bonded to four equivalent Sb3- atoms to form a mixture of edge and corner-sharing CuSb4 tetrahedra. All Cu–Sb bond lengths are 2.67 Å. In the second Cu+1.50+ site, Cu+1.50+ is bonded in a 5-coordinate geometry to five Sb3- atoms. There are one shorter (2.53 Å) and four longer (2.72 Å) Cu–Sb bond lengths. There are two inequivalent Sb3- sites. In the first Sb3- site, Sb3- is bonded to four equivalent Eu3+ and four equivalent Cu+1.50+ atoms to form a mixture of distorted edge and face-sharing SbEu4Cu4 tetrahedra. In the second Sb3- site, Sb3- is bonded in a 9-coordinate geometry to four equivalent Eu3+ and five Cu+1.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Eu(BS2)2 by Materials Project

Eu(BS2)2 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Eu2+ is bonded in a 9-coordinate geometry to nine S2- atoms. There are a spread of Eu–S bond distances ranging from 2.94–3.55 Å. There are two inequivalent B3+ sites. In the first B3+ site, B3+ is bonded to four S2- atoms to form corner-sharing BS4 tetrahedra. There are a spread of B–S bond distances ranging from 1.92–1.95 Å. In the second B3+ site, B3+ is bonded to four S2- atoms to form a mixture of corner and edge-sharing BS4 tetrahedra. There are a spread of B–S bond distances ranging from 1.88–1.97 Å. There are four inequivalent S2- sites. In the first S2- site, S2- is bonded in a 2-coordinate geometry to two equivalent Eu2+ and two B3+ atoms. In the second S2- site, S2- is bonded in a distorted water-like geometry to two equivalent Eu2+ and two equivalent B3+ atoms. In the third S2- site, S2- is bonded in a 2-coordinate geometry to three equivalent Eu2+ and two equivalent B3+ atoms. In the fourth S2- site, S2- is bonded in a 2-coordinate geometry to two equivalent Eu2+ and two B3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Eu(ErS2)2 by Materials Project

Eu(ErS2)2 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are two inequivalent Er3+ sites. In the first Er3+ site, Er3+ is bonded to six S2- atoms to form a mixture of edge and corner-sharing ErS6 octahedra. The corner-sharing octahedra tilt angles range from 48–65°. There are a spread of Er–S bond distances ranging from 2.66–2.75 Å. In the second Er3+ site, Er3+ is bonded to six S2- atoms to form a mixture of edge and corner-sharing ErS6 octahedra. The corner-sharing octahedra tilt angles range from 48–65°. There are a spread of Er–S bond distances ranging from 2.69–2.74 Å. Eu2+ is bonded in a 8-coordinate geometry to eight S2- atoms. There are a spread of Eu–S bond distances ranging from 3.04–3.29 Å. There are four inequivalent S2- sites. In the first S2- site, S2- is bonded to three equivalent Er3+ and two equivalent Eu2+ atoms to form a mixture of distorted edge and corner-sharing SEu2Er3 square pyramids. In the second S2- site, S2- is bonded in a 5-coordinate geometry to three Er3+ and two equivalent Eu2+ atoms. In the third S2- site, S2- is bonded to three equivalent Er3+ and two equivalent Eu2+ atoms to form a mixture of distorted edge and corner-sharing SEu2Er3 trigonal bipyramids. In the fourth S2- site, S2- is bonded in a 5-coordinate geometry to three Er3+ and two equivalent Eu2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Eu(IO3)3 by Materials Project

Eu(O3I)3 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Eu3+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Eu–O bond distances ranging from 2.39–2.97 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Eu3+ and one I5+ atom. The O–I bond length is 1.86 Å. In the second O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Eu3+ and one I5+ atom. The O–I bond length is 1.83 Å. In the third O2- site, O2- is bonded in a 2-coordinate geometry to one Eu3+ and one I5+ atom. The O–I bond length is 1.84 Å. In the fourth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Eu3+ and one I5+ atom. The O–I bond length is 1.83 Å. In the fifth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Eu3+ and two I5+ atoms. There are one shorter (1.85 Å) and one longer (2.89 Å) O–I bond lengths. In the sixth O2- site, O2- is bonded in a 2-coordinate geometry to one Eu3+ and one I5+ atom. The O–I bond length is 1.83 Å. In the seventh O2- site, O2- is bonded in a distorted single-bond geometry to two I5+ atoms. There are one shorter (1.83 Å) and one longer (2.81 Å) O–I bond lengths. In the eighth O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent I5+ atoms. There are one shorter (1.86 Å) and one longer (2.43 Å) O–I bond lengths. In the ninth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Eu3+ and one I5+ atom. The O–I bond length is 1.84 Å. There are three inequivalent I5+ sites. In the first I5+ site, I5+ is bonded in a 6-coordinate geometry to six O2- atoms. In the second I5+ site, I5+ is bonded in a 3-coordinate geometry to three O2- atoms. In the third I5+ site, I5+ is bonded in a 3-coordinate geometry to three O2- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Eu(NiSb)2 by Materials Project

Eu(NiSb)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Eu2+ is bonded in a distorted body-centered cubic geometry to eight equivalent Sb3- atoms. All Eu–Sb bond lengths are 3.44 Å. Ni2+ is bonded to four equivalent Sb3- atoms to form a mixture of edge and corner-sharing NiSb4 tetrahedra. All Ni–Sb bond lengths are 2.51 Å. Sb3- is bonded in a 9-coordinate geometry to four equivalent Eu2+, four equivalent Ni2+, and one Sb3- atom. The Sb–Sb bond length is 2.95 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Eu(Ni2B)6 by Materials Project

Eu(Ni2B)6 crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Eu2+ is bonded in a hexagonal planar geometry to six equivalent B3- atoms. All Eu–B bond lengths are 3.16 Å. There are two inequivalent Ni+1.33+ sites. In the first Ni+1.33+ site, Ni+1.33+ is bonded in a T-shaped geometry to three equivalent B3- atoms. There are two shorter (2.07 Å) and one longer (2.09 Å) Ni–B bond lengths. In the second Ni+1.33+ site, Ni+1.33+ is bonded to four equivalent B3- atoms to form a mixture of distorted edge and corner-sharing NiB4 trigonal pyramids. There are two shorter (2.04 Å) and two longer (2.10 Å) Ni–B bond lengths. B3- is bonded in a 7-coordinate geometry to one Eu2+ and seven Ni+1.33+ atoms.

36 MATERIALS SCIENCE↗