Title: Influence of magnetism on Dirac semimetallic behavior in nonstoichiometric ${\mathrm{Sr}}_{1-y}{\mathrm{Mn}}_{1-z}{\mathrm{Sb}}_2\left(y~0.07,z~0.02\right)$

Abstract

Nonstoichiometric Sr_1-yMn_1-zSb₂(y,z < 0.1) is known to exhibit a coexistence of magnetic order and the nontrivial semimetallic behavior. Here, we report the magnetism and its strong coupling to the semimetallic behavior, by a combined use of inelastic neutron scattering (INS) and density functional theory (DFT). A phase separation consisting of a majority antiferromagentic phase and a minority ferromagnetic phase is proposed. We found a relatively large spin excitation gap ≈ 8.5meV at 5 K, and the interlayer magnetic exchange constant only 2.8% of the dominant intralayer magnetic interaction, evidencing a quasi-2D magnetism in Sr_1-yMn_1-zSb₂. Using DFT, we find a strong influence of magnetic orders on the electronic band structure and the Dirac dispersions near the Fermi level along the Y-S direction in the presence of a ferromagnetic order. Furthermore, we demonstrate that the size of the ferromagnetic ordered moment is an effective strategy to tune Dirac/Weyl dispersions near the Fermi level. Lastly, our study unveils novel interplay between the magnetic order, ordered moment, and electronic band topology in Sr_1-yMn_1-zSb₂ and opens pathways to control the relativistic band structure.

Authors:

Zhang, Qiang  ^[1];

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Okamoto, Satoshi  ^[2];

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Stone, Matthew B.  ^[2];

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Liu, Jinyu ^[3]; Zhu, Yanglin ^[3]; DiTusa, John ^[4]; Mao, Zhiqiang ^[5]; Tennant, Alan  ^[2]

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+ Show Author Affiliations

1. Louisiana State Univ., Baton Rouge, LA (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
3. Tulane Univ., New Orleans, LA (United States)
4. Louisiana State Univ., Baton Rouge, LA (United States)
5. Tulane Univ., New Orleans, LA (United States) ; Pennsylvania State Univ., University Park, PA (United States)

Publication Date:

2019-11-05

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:

1607177

Grant/Contract Number:  

AC05-00OR22725; SC0012432

Resource Type:

Accepted Manuscript

Journal Name:

Physical Review B

Additional Journal Information:

Journal Volume: 100; Journal Issue: 20; Journal ID: ISSN 2469-9950

Publisher:

American Physical Society (APS)

Country of Publication:

United States

Language:

English

Subject:

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Electronic structure; Spin dynamics; Dirac semimetal; Density functional theory; Inelastic neutron scattering