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Title: Toward the Mott state with magnetic cluster formation in heavily Cu-doped NaFe 1 - x Cu x As

Abstract

Recent neutron scattering measurements imply that NaFe$$_{1-x}$$Cu$$_{x}$$As forms an antiferromagnetic stripe phase near $$x\approx 0.5$$ in a Mott insulating state. This copper concentration is well in excess of that required for superconductivity, $x < 0.04$. We have investigated the development of magnetism in this compound using $$^{23}$$Na nuclear magnetic resonance (NMR) spectra and spin-lattice relaxation measurements performed on single crystals ($x$ = 0.13, 0.18, 0.24, and 0.39). We find multiple inequivalent Na sites, each of which is associated with a different number of nearest neighbor Fe sites occupied by a Cu dopant. We show that the distribution of Cu substituted for Fe is random in-plane for low concentrations ($x = 0.13$ and 0.18), but deviates from this with increasing Cu doping. As is characteristic of many pnictide compounds, there is a spin pseudo gap that increases in magnitude with dopant concentration. This is correlated with a corresponding increase in orbital NMR frequency shift indicating a change in valence from Cu$$^{2+}$$ to a Cu$$^{1+}$$ state as $x$ exceeds 0.18, concomitant with the change of Fe$$^{2+}$$ to Fe$$^{3+}$$ resulting in the formation of magnetic clusters. Yet, for $$x\leq 0.39$$ there is no evidence of long-range static magnetic order.

Authors:
 [1];  [1];  [1];  [2];  [3];  [1]
  1. Northwestern Univ., Evanston, IL (United States)
  2. Rice Univ., Houston, TX (United States); Univ. of California, Berkeley, CA (United States)
  3. Rice Univ., Houston, TX (United States)
Publication Date:
Research Org.:
Northwestern Univ., Evanston, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1506097
Alternate Identifier(s):
OSTI ID: 1505669
Grant/Contract Number:  
FG02-05ER46248; FG02-05ER46202; SC0012311
Resource Type:
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 99; Journal Issue: 15; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Antiferromagnetism; Stripes; Mott Insulators; Pnictides; Strongly correlated systems; Nuclear magnetic resonance

Citation Formats

Xin, Yizhou, Stolt, Ingrid, Lee, Jeongseop A., Song, Yu, Dai, Pengcheng, and Halperin, W. P. Toward the Mott state with magnetic cluster formation in heavily Cu-doped NaFe1-xCuxAs. United States: N. p., 2019. Web. doi:10.1103/PhysRevB.99.155114.
Xin, Yizhou, Stolt, Ingrid, Lee, Jeongseop A., Song, Yu, Dai, Pengcheng, & Halperin, W. P. Toward the Mott state with magnetic cluster formation in heavily Cu-doped NaFe1-xCuxAs. United States. doi:10.1103/PhysRevB.99.155114.
Xin, Yizhou, Stolt, Ingrid, Lee, Jeongseop A., Song, Yu, Dai, Pengcheng, and Halperin, W. P. Mon . "Toward the Mott state with magnetic cluster formation in heavily Cu-doped NaFe1-xCuxAs". United States. doi:10.1103/PhysRevB.99.155114.
@article{osti_1506097,
title = {Toward the Mott state with magnetic cluster formation in heavily Cu-doped NaFe1-xCuxAs},
author = {Xin, Yizhou and Stolt, Ingrid and Lee, Jeongseop A. and Song, Yu and Dai, Pengcheng and Halperin, W. P.},
abstractNote = {Recent neutron scattering measurements imply that NaFe$_{1-x}$Cu$_{x}$As forms an antiferromagnetic stripe phase near $x\approx 0.5$ in a Mott insulating state. This copper concentration is well in excess of that required for superconductivity, $x < 0.04$. We have investigated the development of magnetism in this compound using $^{23}$Na nuclear magnetic resonance (NMR) spectra and spin-lattice relaxation measurements performed on single crystals ($x$ = 0.13, 0.18, 0.24, and 0.39). We find multiple inequivalent Na sites, each of which is associated with a different number of nearest neighbor Fe sites occupied by a Cu dopant. We show that the distribution of Cu substituted for Fe is random in-plane for low concentrations ($x = 0.13$ and 0.18), but deviates from this with increasing Cu doping. As is characteristic of many pnictide compounds, there is a spin pseudo gap that increases in magnitude with dopant concentration. This is correlated with a corresponding increase in orbital NMR frequency shift indicating a change in valence from Cu$^{2+}$ to a Cu$^{1+}$ state as $x$ exceeds 0.18, concomitant with the change of Fe$^{2+}$ to Fe$^{3+}$ resulting in the formation of magnetic clusters. Yet, for $x\leq 0.39$ there is no evidence of long-range static magnetic order.},
doi = {10.1103/PhysRevB.99.155114},
journal = {Physical Review B},
number = 15,
volume = 99,
place = {United States},
year = {2019},
month = {4}
}

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