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9 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Phonon modes and Raman signatures of MnBi 2n Te 3n+1 (n=1,2,3,4) magnetic topological heterostructures

An intrinsic antiferromagnetic topological insulator MnBi 2 Te 4 arises when intercalating a Mn-Te bilayer chain in a topological insulator, Bi 2 Te 3 . We present observations on the inter- and intralayer phonon modes of the generalized MnBi 2n Te 3n+1 (n=1,2,3,4) family using cryogenic low-frequency Raman spectroscopy with various polarization configurations. Two peaks at 66 and 112 cm –1 show abnormal perturbation in Raman linewidths below magnetic transition temperature due to spin-phonon coupling. In MnBi 4 Te 7 , B i2 Te 3 layers induce Davydov splitting of the A1g mode around 137 cm –1 at 5 K. The out-of-plane interlayer force constant estimated using the linear chain model was (3.98±0.14)×10 19 N/m 3 , three times weaker than that of Bi 2 Te 3 . Adding more Bi 2 Te 3 layers, such as MnBi 6 Te 10 and MnBi 8 Te 13 , makes Bi 2 Te 3 properties more dominant than magnetic properties. Our work experimentally and theoretically discovers the dynamics of phonon modes of MnBi 2n Te 3n+ 1 family, facilitating utilization of magnetic topological heterostructures.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2020

Materials Data on MnTe by Materials Project

MnTe is Halite, Rock Salt structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Mn2+ is bonded to six equivalent Te2- atoms to form a mixture of edge and corner-sharing MnTe6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Mn–Te bond lengths are 2.88 Å. Te2- is bonded to six equivalent Mn2+ atoms to form a mixture of edge and corner-sharing TeMn6 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MnTe2 by Materials Project

MnTe2 is Pyrite structured and crystallizes in the cubic Pa-3 space group. The structure is three-dimensional. Mn4+ is bonded to six equivalent Te2- atoms to form corner-sharing MnTe6 octahedra. The corner-sharing octahedral tilt angles are 62°. All Mn–Te bond lengths are 2.76 Å. Te2- is bonded in a distorted trigonal planar geometry to three equivalent Mn4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MnTe by Materials Project

MnTe is Molybdenum Carbide MAX Phase-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Mn2+ is bonded to six equivalent Te2- atoms to form a mixture of edge, face, and corner-sharing MnTe6 octahedra. The corner-sharing octahedral tilt angles are 51°. All Mn–Te bond lengths are 2.85 Å. Te2- is bonded in a 6-coordinate geometry to six equivalent Mn2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MnTe by Materials Project

MnTe is Hausmannite-like structured and crystallizes in the monoclinic Pm space group. The structure is three-dimensional. there are four inequivalent Mn2+ sites. In the first Mn2+ site, Mn2+ is bonded to six Te2- atoms to form distorted MnTe6 octahedra that share corners with nine MnTe4 tetrahedra, edges with six MnTe6 octahedra, and a faceface with one MnTe4 tetrahedra. There are a spread of Mn–Te bond distances ranging from 2.76–3.15 Å. In the second Mn2+ site, Mn2+ is bonded to four Te2- atoms to form MnTe4 tetrahedra that share corners with nine MnTe6 octahedra, corners with two equivalent MnTe4 tetrahedra, edges with two equivalent MnTe4 tetrahedra, and a faceface with one MnTe6 octahedra. The corner-sharing octahedra tilt angles range from 53–61°. There are a spread of Mn–Te bond distances ranging from 2.61–2.71 Å. In the third Mn2+ site, Mn2+ is bonded to four Te2- atoms to form MnTe4 tetrahedra that share corners with nine MnTe6 octahedra, corners with two equivalent MnTe4 tetrahedra, edges with two equivalent MnTe4 tetrahedra, and a faceface with one MnTe6 octahedra. The corner-sharing octahedra tilt angles range from 53–61°. There are a spread of Mn–Te bond distances ranging from 2.61–2.70 Å. In the fourth Mn2+ site, Mn2+ is bonded to six Te2- atoms to form distorted MnTe6 octahedra that share corners with nine MnTe4 tetrahedra, edges with six MnTe6 octahedra, and a faceface with one MnTe4 tetrahedra. There are a spread of Mn–Te bond distances ranging from 2.77–3.14 Å. There are four inequivalent Te2- sites. In the first Te2- site, Te2- is bonded to four Mn2+ atoms to form a mixture of distorted corner and edge-sharing TeMn4 trigonal pyramids. In the second Te2- site, Te2- is bonded in a 6-coordinate geometry to six Mn2+ atoms. In the third Te2- site, Te2- is bonded to four Mn2+ atoms to form a mixture of distorted corner and edge-sharing TeMn4 trigonal pyramids. In the fourth Te2- site, Te2- is bonded in a 6-coordinate geometry to six Mn2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MnTe by Materials Project

MnTe is Zincblende, Sphalerite structured and crystallizes in the cubic F-43m space group. The structure is three-dimensional. Mn2+ is bonded to four equivalent Te2- atoms to form corner-sharing MnTe4 tetrahedra. All Mn–Te bond lengths are 2.77 Å. Te2- is bonded to four equivalent Mn2+ atoms to form corner-sharing TeMn4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mn3Te by Materials Project

Mn3Te is alpha bismuth trifluoride structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. there are two inequivalent Mn sites. In the first Mn site, Mn is bonded to four equivalent Mn and four equivalent Te atoms to form a mixture of distorted edge, corner, and face-sharing MnMn4Te4 tetrahedra. All Mn–Mn bond lengths are 2.59 Å. All Mn–Te bond lengths are 2.59 Å. In the second Mn site, Mn is bonded in a 8-coordinate geometry to eight equivalent Mn and six equivalent Te atoms. All Mn–Te bond lengths are 2.99 Å. Te is bonded in a distorted body-centered cubic geometry to fourteen Mn atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mn3Te by Materials Project

Mn3Te is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are two inequivalent Mn sites. In the first Mn site, Mn is bonded in a 12-coordinate geometry to eight equivalent Mn and four equivalent Te atoms. There are a spread of Mn–Mn bond distances ranging from 2.48–2.96 Å. There are two shorter (2.72 Å) and two longer (2.77 Å) Mn–Te bond lengths. In the second Mn site, Mn is bonded in a 12-coordinate geometry to eight equivalent Mn and four equivalent Te atoms. There are a spread of Mn–Mn bond distances ranging from 2.48–2.96 Å. There are two shorter (2.72 Å) and two longer (2.77 Å) Mn–Te bond lengths. Te is bonded to twelve Mn atoms to form a mixture of face and corner-sharing TeMn12 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MnTe by Materials Project

MnTe is Modderite structured and crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Mn2+ is bonded in a 6-coordinate geometry to six equivalent Te2- atoms. There are a spread of Mn–Te bond distances ranging from 2.78–2.99 Å. Te2- is bonded to six equivalent Mn2+ atoms to form a mixture of distorted corner, edge, and face-sharing TeMn6 octahedra. The corner-sharing octahedra tilt angles range from 42–52°.

36 MATERIALS SCIENCE↗