Vacancy Tuned Antiferromagnetism in the Candidate Topological Semimetal LaMn_xSb₂

We report the magnetic and transport properties of LaMn_xSb₂, an underexplored member of the 1-1-2 family of topological semimetals. LaMn_xSb₂ crystalizes in the tetragonal P₄/nmm space group with intrinsic Mn vacancies (x < 1). We use a Sb-flux to prepare single crystals of LaMn_xSb₂ with x = 0.76–0.92 and find LaMn_xSb₂ has a rich temperature–composition magnetic phase diagram, ordering antiferromagnetically below T_N1 = 130–170 K with additional transitions at lower temperatures. Depending on x, our magnetic and transport measurements provide evidence for at least three unique antiferromagnetic states in LaMn_xSb₂. This contradicts previous reports of ferromagnetism found in polycrystalline LaMn_xSb₂,¹ which we ascribe to a MnSb impurity. Results of powder neutron diffraction to determine the ordering wave vectors of LaMn_xSb₂ (x = 0.92) will be discussed.

 

¹Sologub O.; Hiebl, K.; Rogl P.; Bodak, O. J. Alloys & Compounds. 1995, 227, 1.