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A New Magnetic Topological Quantum Material Candidate by Design.

Authors :: Gui X
Pletikosic I
Cao H
Tien HJ
Xu X
Zhong R
Wang G
Chang TR
Jia S
Valla T
Xie W
Cava RJ
Source :: ACS central science [ACS Cent Sci] 2019 May 22; Vol. 5 (5), pp. 900-910. Date of Electronic Publication: 2019 Apr 19.
Publication Year :: 2019
Abstract: Magnetism, when combined with an unconventional electronic band structure, can give rise to forefront electronic properties such as the quantum anomalous Hall effect, axion electrodynamics, and Majorana fermions. Here we report the characterization of high-quality crystals of EuSn <subscript>2</subscript> P <subscript>2</subscript> , a new quantum material specifically designed to engender unconventional electronic states plus magnetism. EuSn <subscript>2</subscript> P <subscript>2</subscript> has a layered, Bi <subscript>2</subscript> Te <subscript>3</subscript> -type structure. Ferromagnetic interactions dominate the Curie-Weiss susceptibility, but a transition to antiferromagnetic ordering occurs near 30 K. Neutron diffraction reveals that this is due to two-dimensional ferromagnetic spin alignment within individual Eu layers and antiferromagnetic alignment between layers-this magnetic state surrounds the Sn-P layers at low temperatures. The bulk electrical resistivity is sensitive to the magnetism. Electronic structure calculations reveal that EuSn <subscript>2</subscript> P <subscript>2</subscript> might be a strong topological insulator, which can be a new magnetic topological quantum material (MTQM) candidate. The calculations show that surface states should be present, and they are indeed observed by angle-resolved photoelectron spectroscopy (ARPES) measurements.<br />Competing Interests: The authors declare no competing financial interest.