Metal-insulator transition in antiferromagnetic Ba1-xKxMn2As2 (0 <= x <= 0.4) single crystals studied by Mn-55 and As-75 NMR

TitleMetal-insulator transition in antiferromagnetic Ba1-xKxMn2As2 (0 <= x <= 0.4) single crystals studied by Mn-55 and As-75 NMR
Publication TypeJournal Article
Year of Publication2013
AuthorsYeninas S, Pandey A, Ogloblichev V, Mikhalev K, Johnston DC, Furukawa Y
Journal TitlePhysical Review B
Volume88
Pages241111
Date Published12
Type of ArticleArticle
ISBN Number1098-0121
Accession NumberWOS:000328888300001
Keywordsla1-xsrxtio3, nuclear-magnetic-resonance, SPIN-LATTICE RELAXATION
Abstract

The magnetic structure and metal-insulator transition in antiferromagnetic (AFM) BaMn2As2 and Ba1-xKxMn2As2 single crystals have been investigated by Mn-55 and As-75 nuclear magnetic resonance (NMR) measurements. In the parent AFM insulator BaMn2As2 with a Neel temperature T-N = 625 K, we observed a Mn-55 zero-field NMR (ZFNMR) spectrum and confirmed the G-type AFM structure from the field dependence of the Mn-55 spectra and As-75 NMR spectra below T-N. In hole-doped crystals with x > 0.01, similar Mn-55 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 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.

URL<Go to ISI>://WOS:000328888300001
DOI10.1103/PhysRevB.88.241111