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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

MnSi 2 Te 4 : A van der Waals Antiferromagnetic Semiconductor with Large Negative Magnetoresistance

Magnetism in van der Waals semiconductors offers significant potential for fundamental research on low-dimensional magnetism and the development of high-performance two-dimensional spintronic devices. Here, we report the growth, physical properties, and first-principles calculations of a new dual-octahedral transition metal chalcogenide (DTMC) MnSi 2 Te 4 . MnSi 2 Te 4 features a layered structure with an intralayer heterostructure, where the metal octahedra and nonmetal dimeric octahedra form zigzag chains alternately. Property characterization reveals that MnSi 2 Te 4 is a collinear G-type antiferromagnetic semiconductor, with a Néel temperature T N of 18.6 K and a significant unsaturated negative magnetoresistance (NMR) reaching −42.5% at 9 T and 100 K. First-principles calculations on the electronic band structure demonstrate that the large NMR primarily originates from the spin splitting due to parity-time symmetry breaking. This study not only discovers a new member of DTMCs with a unique crystal structure and large NMR, but also establishes a promising platform for investigating next-generation spintronic devices.

Liao, Ke [Chinese Academy of Sciences (CAS), Beiji↗
DOE OSTI2020

Materials Data on La3Y(MnSi)4 by Materials Project

La3Y(MnSi)4 crystallizes in the tetragonal P4mm space group. The structure is two-dimensional and consists of one La3Y(MnSi)4 sheet oriented in the (0, 0, 1) direction. there are three inequivalent La sites. In the first La site, La is bonded in a 4-coordinate geometry to four equivalent Si atoms. All La–Si bond lengths are 3.05 Å. In the second La site, La is bonded in a 4-coordinate geometry to four equivalent Y, four equivalent Mn, and five Si atoms. All La–Y bond lengths are 3.88 Å. All La–Mn bond lengths are 3.23 Å. There are four shorter (3.06 Å) and one longer (3.52 Å) La–Si bond lengths. In the third La site, La is bonded in a 4-coordinate geometry to four equivalent Si atoms. All La–Si bond lengths are 3.05 Å. Y is bonded in a 4-coordinate geometry to four equivalent La, four equivalent Mn, and four equivalent Si atoms. All Y–Mn bond lengths are 3.02 Å. All Y–Si bond lengths are 2.96 Å. There are two inequivalent Mn sites. In the first Mn site, Mn is bonded to two equivalent Y and four Si atoms to form a mixture of distorted edge, face, and corner-sharing MnY2Si4 tetrahedra. There are two shorter (2.42 Å) and two longer (2.44 Å) Mn–Si bond lengths. In the second Mn site, Mn is bonded to two equivalent La and four Si atoms to form a mixture of distorted edge, face, and corner-sharing MnLa2Si4 tetrahedra. There are two shorter (2.41 Å) and two longer (2.42 Å) Mn–Si bond lengths. There are four inequivalent Si sites. In the first Si site, Si is bonded in a 8-coordinate geometry to four equivalent La and four equivalent Mn atoms. In the second Si site, Si is bonded in a 8-coordinate geometry to four equivalent La and four equivalent Mn atoms. In the third Si site, Si is bonded in a 9-coordinate geometry to one La, four equivalent Y, and four equivalent Mn atoms. In the fourth Si site, Si is bonded in a 8-coordinate geometry to four equivalent La and four equivalent Mn atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Topological energy barrier for skyrmion lattice formation in MnSi

We report the direct measurement of the topological skyrmion energy barrier through a hysteresis of the skyrmion lattice in the chiral magnet MnSi. Measurements were made using small-angle neutron scattering with a custom-built resistive coil to allow for high-precision minor hysteresis loops. The experimental data were analyzed using an adapted Preisach model to quantify the energy barrier for skyrmion formation and corroborated by the minimum-energy path analysis based on atomistic spin simulations. Here, we reveal that the skyrmion lattice in MnSi forms from the conical phase progressively in small domains, each of which consisting of hundreds of skyrmions, and with an activation barrier of several eV.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

Entropic signatures of the skyrmion lattice phase in MnSi 1- x Al x and Fe 1- y Co y Si

Here, the entropic signatures of magnetic phase transitions in the skyrmion lattice host compounds MnSi 0.962 Al 0.038 and Fe 0.7 Co 0.3 Si were investigated through low field magnetization and ac susceptibility measurements. These data indicate that the conical to skyrmion transition that occurs with the application of magnetic field in MnSi 0.962 Al 0.038 is characterized by clear discontinuity in the magnetic entropy as expected for first order topological phase transition. These same magnetoentropic features are negligibly small in isostructural Fe 0.7 Co 0.3 Si due to the level of chemical substitution related disorder and differences in the spin dynamics (range and timescales). Despite the obvious similarities in the magnetic structures of these two compounds, the transitions between these phases is substantially different indicating a surprising nonuniversality to the magnetic phase transitions in this class of materials.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Skyrmion lattice manipulation with electric currents and thermal gradients in MnSi

The skyrmion lattice (SkL) in MnSi was studied using small-angle neutron scattering and under the influence of a radial electric current in a Corbino geometry. In response to the applied current, the SkL undergoes an angular reorientation with respect to the MnSi crystal lattice. The reorientation is nonmonotonic with increasing current, with the SkL rotating first in one direction and then the other. The SkL reorientation was studied at different sample locations and found to depend on the local current density as inferred from a finite-element analysis. Here, the nonmonotonic response indicates the presence of two competing effects on the SkL, most likely due to the presence of both radial electric and thermal currents. Such a scenario is supported by micromagnetic simulations, which show how these effects can act constructively or destructively to drive the SkL rotation, depending on the direction of the electric current. In addition, the simulations also suggest how the direction of the skyrmion flow may affect the SkL orientation.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2023

Magnetic molecular orbitals in MnSi

A large body of knowledge about magnetism is attained from models of interacting spins, which usually reside on magnetic ions. Proposals beyond the ionic picture are uncommon and seldom verified by direct observations in conjunction with microscopic theory. Here, using inelastic neutron scattering to study the itinerant near-ferromagnet MnSi, we find that the system’s fundamental magnetic units are interconnected, extended molecular orbitals consisting of three Mn atoms each rather than individual Mn atoms. This result is further corroborated by magnetic Wannier orbitals obtained by ab initio calculations. It contrasts the ionic picture with a concrete example and presents an unexplored regime of the spin waves where the wavelength is comparable to the spatial extent of the molecular orbitals. Our discovery brings important insights into not only the magnetism of MnSi but also a broad range of magnetic quantum materials where structural symmetry, electron itinerancy, and correlations act in concert.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

Materials Data on MnSi by Materials Project

MnSi is alpha-derived structured and crystallizes in the cubic P2_13 space group. The structure is three-dimensional. Mn4+ is bonded in a 7-coordinate geometry to seven equivalent Si4- atoms. There are a spread of Mn–Si bond distances ranging from 2.28–2.53 Å. Si4- is bonded in a 7-coordinate geometry to seven equivalent Mn4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Th(MnSi)2 by Materials Project

Th(MnSi)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Th4+ is bonded in a body-centered cubic geometry to eight equivalent Si4- atoms. All Th–Si bond lengths are 3.10 Å. Mn2+ is bonded to four equivalent Si4- atoms to form a mixture of edge and corner-sharing MnSi4 tetrahedra. All Mn–Si bond lengths are 2.39 Å. Si4- is bonded in a 9-coordinate geometry to four equivalent Th4+, four equivalent Mn2+, and one Si4- atom. The Si–Si bond length is 2.57 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LuSc3(MnSi)4 by Materials Project

LuSc3(MnSi)4 crystallizes in the monoclinic Pm space group. The structure is three-dimensional. Lu is bonded in a 5-coordinate geometry to five Si atoms. There are a spread of Lu–Si bond distances ranging from 2.84–2.87 Å. There are three inequivalent Sc sites. In the first Sc site, Sc is bonded in a 5-coordinate geometry to five Si atoms. There are a spread of Sc–Si bond distances ranging from 2.77–2.84 Å. In the second Sc site, Sc is bonded in a 5-coordinate geometry to five Si atoms. There are a spread of Sc–Si bond distances ranging from 2.77–2.86 Å. In the third Sc site, Sc is bonded in a 5-coordinate geometry to five Si atoms. There are two shorter (2.75 Å) and three longer (2.80 Å) Sc–Si bond lengths. There are four inequivalent Mn sites. In the first Mn site, Mn is bonded to four Si atoms to form distorted corner-sharing MnSi4 tetrahedra. There are a spread of Mn–Si bond distances ranging from 2.41–2.50 Å. In the second Mn site, Mn is bonded to four Si atoms to form distorted corner-sharing MnSi4 tetrahedra. There are a spread of Mn–Si bond distances ranging from 2.42–2.56 Å. In the third Mn site, Mn is bonded in a 4-coordinate geometry to four Si atoms. There are a spread of Mn–Si bond distances ranging from 2.42–2.62 Å. In the fourth Mn site, Mn is bonded in a 4-coordinate geometry to four Si atoms. There are a spread of Mn–Si bond distances ranging from 2.43–2.62 Å. There are four inequivalent Si sites. In the first Si site, Si is bonded in a 9-coordinate geometry to one Lu, four Sc, and four Mn atoms. In the second Si site, Si is bonded in a 9-coordinate geometry to five Sc and four Mn atoms. In the third Si site, Si is bonded in a 9-coordinate geometry to two equivalent Lu, three Sc, and four Mn atoms. In the fourth Si site, Si is bonded in a 9-coordinate geometry to two equivalent Lu, three Sc, and four Mn atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ThU(MnSi)4 by Materials Project

UTh(MnSi)4 crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. U4+ is bonded in a distorted body-centered cubic geometry to eight equivalent Si4- atoms. All U–Si bond lengths are 3.05 Å. Th4+ is bonded in a body-centered cubic geometry to eight equivalent Si4- atoms. All Th–Si bond lengths are 3.08 Å. Mn2+ is bonded to four Si4- atoms to form a mixture of edge and corner-sharing MnSi4 tetrahedra. There are two shorter (2.36 Å) and two longer (2.39 Å) Mn–Si bond lengths. There are two inequivalent Si4- sites. In the first Si4- site, Si4- is bonded in a 9-coordinate geometry to four equivalent Th4+, four equivalent Mn2+, and one Si4- atom. The Si–Si bond length is 2.57 Å. In the second Si4- site, Si4- is bonded in a 9-coordinate geometry to four equivalent U4+, four equivalent Mn2+, and one Si4- atom. The Si–Si bond length is 2.39 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LaCe(MnSi)4 by Materials Project

CeLa(MnSi)4 crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. Ce3+ is bonded in a body-centered cubic geometry to eight equivalent Si4- atoms. All Ce–Si bond lengths are 3.09 Å. La3+ is bonded in a body-centered cubic geometry to eight equivalent Si4- atoms. All La–Si bond lengths are 3.12 Å. Mn+2.50+ is bonded to four Si4- atoms to form a mixture of edge and corner-sharing MnSi4 tetrahedra. There are two shorter (2.38 Å) and two longer (2.39 Å) Mn–Si bond lengths. There are two inequivalent Si4- sites. In the first Si4- site, Si4- is bonded in a 9-coordinate geometry to four equivalent Ce3+, four equivalent Mn+2.50+, and one Si4- atom. The Si–Si bond length is 2.55 Å. In the second Si4- site, Si4- is bonded in a 9-coordinate geometry to four equivalent La3+, four equivalent Mn+2.50+, and one Si4- atom. The Si–Si bond length is 2.72 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on La2Nd(MnSi)6 by Materials Project

NdLa2(MnSi)6 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Nd3+ is bonded in a body-centered cubic geometry to eight equivalent Si4- atoms. All Nd–Si bond lengths are 3.12 Å. La3+ is bonded in a body-centered cubic geometry to eight Si4- atoms. There are four shorter (3.13 Å) and four longer (3.14 Å) La–Si bond lengths. There are two inequivalent Mn+2.50+ sites. In the first Mn+2.50+ site, Mn+2.50+ is bonded to four Si4- atoms to form a mixture of corner and edge-sharing MnSi4 tetrahedra. All Mn–Si bond lengths are 2.39 Å. In the second Mn+2.50+ site, Mn+2.50+ is bonded to four equivalent Si4- atoms to form a mixture of corner and edge-sharing MnSi4 tetrahedra. All Mn–Si bond lengths are 2.38 Å. There are three inequivalent Si4- sites. In the first Si4- site, Si4- is bonded in a 9-coordinate geometry to four equivalent Nd3+, four equivalent Mn+2.50+, and one Si4- atom. The Si–Si bond length is 2.65 Å. In the second Si4- site, Si4- is bonded in a 9-coordinate geometry to four equivalent La3+, four equivalent Mn+2.50+, and one Si4- atom. The Si–Si bond length is 2.72 Å. In the third Si4- site, Si4- is bonded in a 9-coordinate geometry to four equivalent La3+, four equivalent Mn+2.50+, and one Si4- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LaPr(MnSi)4 by Materials Project

PrLa(MnSi)4 crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. Pr3+ is bonded in a body-centered cubic geometry to eight equivalent Si4- atoms. All Pr–Si bond lengths are 3.13 Å. La3+ is bonded in a body-centered cubic geometry to eight equivalent Si4- atoms. All La–Si bond lengths are 3.14 Å. Mn+2.50+ is bonded to four Si4- atoms to form a mixture of corner and edge-sharing MnSi4 tetrahedra. There are two shorter (2.38 Å) and two longer (2.39 Å) Mn–Si bond lengths. There are two inequivalent Si4- sites. In the first Si4- site, Si4- is bonded in a 9-coordinate geometry to four equivalent La3+, four equivalent Mn+2.50+, and one Si4- atom. The Si–Si bond length is 2.72 Å. In the second Si4- site, Si4- is bonded in a 9-coordinate geometry to four equivalent Pr3+, four equivalent Mn+2.50+, and one Si4- atom. The Si–Si bond length is 2.68 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Quasiparticle characteristics of the weakly ferromagnetic Hund metal MnSi

Hund metals are multiorbital systems with 3d or 4d electrons exhibiting both an itinerant character and local moments, and they feature Kondo-like screenings of local orbital and spin moments, with suppressed coherence temperatures driven by Hund's coupling J H . They often exhibit magnetic order at low temperature, but how the interaction between the Kondo-like screening and long-range magnetic order is manifested in the quasiparticle spectrum remains an open question. Here, we present the spectroscopic signature of such an interaction in a Hund metal candidate MnSi exhibiting weak ferromagnetism. Our photoemission measurements reveal renormalized quasiparticle bands near the Fermi level with strong momentum dependence: The ferromagnetism manifests through possibly exchange-split bands (Q1) below T C , while the spin/orbital screenings lead to the gradual development of quasiparticles (Q2) upon cooling. Our results demonstrate how the characteristic spin/orbital coherence in a Hund metal could coexist and compete with the magnetic order to form a weak itinerant ferromagnet, via quasiparticle bands that are well separated in momentum space and exhibit distinct temperature dependence. Here, our results imply that the competition between the spin/orbital screening and the magnetic order in a Hund metal bears interesting similarities to the Kondo lattice systems

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

Materials Data on Yb(MnSi)2 by Materials Project

YbMn2Si2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Yb3+ is bonded in a body-centered cubic geometry to eight equivalent Si4- atoms. All Yb–Si bond lengths are 3.06 Å. Mn+2.50+ is bonded to four equivalent Si4- atoms to form a mixture of corner and edge-sharing MnSi4 tetrahedra. All Mn–Si bond lengths are 2.36 Å. Si4- is bonded in a 9-coordinate geometry to four equivalent Yb3+, four equivalent Mn+2.50+, and one Si4- atom. The Si–Si bond length is 2.55 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sm(MnSi)2 by Materials Project

SmMn2Si2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Sm3+ is bonded in a body-centered cubic geometry to eight equivalent Si4- atoms. All Sm–Si bond lengths are 3.07 Å. Mn+2.50+ is bonded to four equivalent Si4- atoms to form a mixture of edge and corner-sharing MnSi4 tetrahedra. All Mn–Si bond lengths are 2.37 Å. Si4- is bonded in a 9-coordinate geometry to four equivalent Sm3+, four equivalent Mn+2.50+, and one Si4- atom. The Si–Si bond length is 2.56 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Gd(MnSi)2 by Materials Project

GdMn2Si2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Gd3+ is bonded in a body-centered cubic geometry to eight equivalent Si4- atoms. All Gd–Si bond lengths are 3.05 Å. Mn+2.50+ is bonded to four equivalent Si4- atoms to form a mixture of edge and corner-sharing MnSi4 tetrahedra. All Mn–Si bond lengths are 2.32 Å. Si4- is bonded in a 9-coordinate geometry to four equivalent Gd3+, four equivalent Mn+2.50+, and one Si4- atom. The Si–Si bond length is 2.55 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pu(MnSi)2 by Materials Project

PuMn2Si2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Pu4+ is bonded in a distorted body-centered cubic geometry to eight equivalent Si4- atoms. All Pu–Si bond lengths are 2.96 Å. Mn2+ is bonded to four equivalent Si4- atoms to form a mixture of edge and corner-sharing MnSi4 tetrahedra. All Mn–Si bond lengths are 2.36 Å. Si4- is bonded in a 9-coordinate geometry to four equivalent Pu4+, four equivalent Mn2+, and one Si4- atom. The Si–Si bond length is 2.37 Å.

36 MATERIALS SCIENCE↗