Magnetic order induces symmetry breaking in the single-crystalline orthorhombic CuMnAs semimetal

Journal Article · 04 December 2017 · Physical Review B

DOI: https://doi.org/10.1103/PhysRevB.96.224405 · OSTI ID:1417664

Emmanouilidou, Eve ^[1]; Cao, Huibo ^[2]; Tang, Peizhe ^[3]; Gui, Xin ^[4]; Hu, Chaowei ^[1]; Shen, Bing ^[1]; Wu, Junyi ^[1]; Zhang, Shou -Cheng ^[5]; Xie, Weiwei ^[4]; Ni, Ni ^[1]

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1. Univ. of California, Los Angeles, CA (United States)
2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
3. Stanford Univ., Stanford, CA (United States)
4. Louisiana State Univ., Baton Rouge, LA (United States)
5. Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)

Recently, orthorhombic CuMnAs has been proposed to be a magnetic material where topological fermions exist around the Fermi level. Here we report the magnetic structure of the orthorhombic Cu_0.95MnAs and Cu_0.98Mn_0.96As single crystals. While Cu_0.95MnAs is a commensurate antiferromagnet below 360 K with a propagation vector of k = 0,Cu_0.98Mn_0.96As undergoes a second-order paramagnetic to incommensurate antiferromagnetic phase transition at 320 K with k = (0.1,0,0), followed by a second-order incommensurate to commensurate antiferromagnetic phase transition at 230 K. In the commensurate antiferromagnetic state, the Mn spins order parallel to the crystallographic b axis but antiparallel to their nearest neighbors, with the spin orientation along the b axis. This magnetic order breaks S_2z, the two-fold rotational symmetry around the c axis, resulting in finite band gaps at the crossing point and the disappearance of the massless topological fermions. Furthermore, our first-principles calculations suggest that orthorhombic CuMnAs can still host spin-polarized surface states and signature induced by nontrivial topology, which makes it a promising candidate for antiferromagnetic spintronics.

• Research Organization: SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: AC02-76SF00515; SC0011978
• OSTI ID: 1417664
• Alternate ID(s): OSTI ID: 1411113
• Journal Information: Physical Review B, Vol. 96, Issue 22; ISSN 2469-9950
• Publisher: American Physical Society (APS)Copyright Statement
• Country of Publication: United States
• Language: English