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Title: Metal-insulator transition in antiferromagnetic Ba 1 - x K x Mn 2 As 2 ( 0 x 0.4 ) single crystals studied by 55 Mn and 75 As NMR

The magnetic structure and metal-insulator transition in antiferromagnetic (AFM) BaMn 2As 2 and Ba 1-xK xMn 2As 2 single crystals have been investigated by 55Mn and 75As nuclear magnetic resonance (NMR) measurements. In the parent AFM insulator BaMn 2As 2 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/T 1) for both nuclei in the doped samples follow the Korringa relation T 1T=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 (T 1T) -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.
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Publication Date:
OSTI Identifier:
Report Number(s):
IS-J 8221
Journal ID: ISSN 1098-0121; PRBMDO
DOE Contract Number:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. B, Condensed Matter and Materials Physics; Journal Volume: 88; Journal Issue: 24
American Physical Society (APS)
Research Org:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States