Title: A-type antiferromagnetic order in MnBi₄Te₇ and MnBi₆Te₁₀ single crystals

Abstract

${\mathrm{MnBi}}_4{\mathrm{Te}}_7$ and ${\mathrm{MnBi}}_6{\mathrm{Te}}_{10}$ are two members with $n=2$ and 3 in the family of ${\mathrm{MnBi}}_{2n}{\mathrm{Te}}_{3n+1}$ where the $n=1$ member, ${\mathrm{MnBi}}_2{\mathrm{Te}}_4$, has been intensively investigated as the first intrinsic antiferromagnetic topological insulator. In this work, we report the A-type antiferromagnetic order in these two compounds by measuring magnetic properties, electrical and thermal transport, specific heat, and single-crystal neutron diffraction. Both compounds order into an A-type antiferromagnetic structure as does ${\mathrm{MnBi}}_2{\mathrm{Te}}_4$ with ferromagnetic planes coupled antiferromagnetically along the crystallographic $c$ axis. While no evidence for any in-plane ordered moment is found for ${\mathrm{MnBi}}_2{\mathrm{Te}}_4$ or ${\mathrm{MnBi}}_6{\mathrm{Te}}_{10}$, weak reflections at half- $L$ positions along the [0 0 $L]$ direction are observed for ${\mathrm{MnBi}}_4{\mathrm{Te}}_7$ suggesting an in-plane ordered moment around $0.15{\mu }_B/\mathrm{Mn}$. The ordering temperature, $T_N$, is 13 K for ${\mathrm{MnBi}}_4{\mathrm{Te}}_7$ and 11 K for ${\mathrm{MnBi}}_6{\mathrm{Te}}_{10}$. The magnetic order is also manifested in the anisotropic magnetic properties. Furthermore, for both compounds, the interlayer coupling is weak and a spin-flip transition occurs when a magnetic field of around 1.6 kOe is applied along the $c$ axis at 2 K. As observed in ${\mathrm{MnBi}}_2{\mathrm{Te}}_4$, when cooling across $T_N$, no anomaly was observed in the temperature dependence of thermopower. On the other hand, critical scattering effects are observed in thermal conductivity although the effect is less pronounced than that in ${\mathrm{MnBi}}_2{\mathrm{Te}}_4$.

Authors:

Yan, J. -Q.  ^[1];

• Search DOE PAGES for author "Yan, J. -Q."
• Search DOE PAGES for ORCID "0000-0001-6625-4706"

Liu, Y. H.  ^[2];

• Search DOE PAGES for author "Liu, Y. H."
• Search DOE PAGES for ORCID "0000-0002-5867-5065"

Parker, D. S.  ^[2];

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• Search DOE PAGES for ORCID "0000-0001-6101-1334"

Wu, Y.  ^[2];

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• Search DOE PAGES for ORCID "0000-0003-1566-614X"

Aczel, A. A.  ^[1];

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• Search DOE PAGES for ORCID "0000-0003-1964-1943"

Matsuda, M.  ^[2];

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• Search DOE PAGES for ORCID "0000-0003-2209-9526"

McGuire, M. A.  ^[2];

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• Search DOE PAGES for ORCID "0000-0003-1762-9406"

Sales, B. C.  ^[2]

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• Search DOE PAGES for ORCID "0000-0002-6335-5912"

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+ Show Author Affiliations

1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States)
2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Publication Date:

Thu May 14 00:00:00 EDT 2020

Research Org.:

Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1649473

Grant/Contract Number:  

AC05-00OR22725

Resource Type:

Accepted Manuscript

Journal Name:

Physical Review Materials

Additional Journal Information:

Journal Volume: 4; Journal Issue: 5; Journal ID: ISSN 2475-9953

Publisher:

American Physical Society (APS)

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; Antiferromagnetism; lattice thermal conductivity; magnetic susceptibility; single crystal materials; topological insulators; crystal growth; DC susceptibility measurements; density functional theory; neutron diffraction