Metal-insulator transition in antiferromagnetic Ba ${}_{1-x}$ K ${}_x$ Mn ${}_2$ As ${}_2$ ( $0\le x\le 0.4$ ) single crystals studied by ${}^{55}$ Mn and ${}^{75}$ As NMR

Journal Article · Mon Dec 23 00:00:00 EST 2013 · Physical Review. B, Condensed Matter and Materials Physics

DOI:https://doi.org/10.1103/PhysRevB.88.241111· OSTI ID:1134208

Yeninas, S.; Pandey, Abhishek; Ogloblichev, V.; Mikhalev, K.; Johnston, D. C.; Furukawa, Y.

The magnetic structure and metal-insulator transition in antiferromagnetic (AFM) BaMn₂As₂ and Ba_1-xK_xMn₂As₂ single crystals have been investigated by ⁵⁵Mn and ⁷⁵As nuclear magnetic resonance (NMR) measurements. In the parent AFM insulator BaMn₂As₂ with a Néel temperature TN=625 K, we observed a ⁵⁵Mn zero-field NMR (ZFNMR) spectrum and confirmed the G-type AFM structure from the field dependence of the ⁵⁵Mn spectra and ⁷⁵As NMR spectra below TN. In hole-doped crystals with x>0.01, similar ⁵⁵Mn ZFNMR spectra were observed and the AFM state was revealed to be robust up to x=0.4 with the ordered moment nearly independent of x. The nuclear spin-lattice relaxation rates (1/T₁) for both nuclei in the doped samples follow the Korringa relation T₁T=const, indicating a metallic state. This confirms the coexistence of AFM ordered localized Mn spins and conduction carriers from a microscopic point of view. From the x dependence of (T₁T)^-1/2 for both nuclei, we conclude that this transition is caused by vanishing of the hole concentration as the transition is approached from the metallic side.

• Research Organization: Ames Lab., Ames, IA (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: AC02-07CH11358
• OSTI ID: 1134208
• Report Number(s): IS-J 8221; PRBMDO
• Journal Information: Physical Review. B, Condensed Matter and Materials Physics, Vol. 88, Issue 24; ISSN 1098-0121
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English

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36 MATERIALS SCIENCE