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Title: Decoupling of magnetism and electric transport in single-crystal (Sr1–xAx)2IrO4 (A = Ca or Ba)

Abstract

Here, we report a systematical structural, transport and magnetic study of Ca or Ba doped Sr2IrO4 single crystals. Isoelectronically substituting Ca2+ (up to 15%) or Ba2+ (up to 4%) ion for the Sr2+ ion provides no additional charge carriers but effectively changes the lattice parameters in Sr2IrO4. In particular, 15% Ca doping considerably reduces the c-axis and the unit cell by nearly 0.45% and 1.00%, respectively. These significant, anisotropic compressions in the lattice parameters conspicuously cause no change in the Néel temperature which remains at 240 K, but drastically reduces the electrical resistivity by up to five orders of magnitude or even precipitates a sharp insulator-to-metal transition at lower temperatures, i.e. the vanishing insulating state accompanies an unchanged Néel temperature in (Sr1–xAx)2IrO4. This observation brings to light an intriguing difference between chemical pressure and applied pressure, the latter of which does suppress the long-range magnetic order in Sr2IrO4. This difference reveals the importance of the Ir1–O2–Ir1 bond angle and homogenous volume compression in determining the magnetic ground state. All results, along with a comparison drawn with results of Tb and La doped Sr2IrO4, underscore that the magnetic transition plays a nonessential role in the formation of the charge gap inmore » the spin–orbit-tuned iridate.« less

Authors:
 [1];  [2];  [1];  [1];  [1]; ORCiD logo [3];  [4]; ORCiD logo [1]
  1. Univ. of Colorado, Boulder, CO (United States)
  2. Univ. of Colorado, Boulder, CO (United States); National High Magnetic Field Lab., Tallahassee, FL (United States)
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  4. Florida State Univ., Tallahassee, FL (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1465028
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Physics. Condensed Matter
Additional Journal Information:
Journal Volume: 30; Journal Issue: 24; Journal ID: ISSN 0953-8984
Publisher:
IOP Publishing
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; spin–orbit coupling; iridates; magnetism; chemical doping

Citation Formats

Zhao, H. D., Terzic, Jasminka, Zheng, Hao, Ni, Y. F., Zhang, Y., Ye, Feng, Schlottmann, P., and Cao, Gang. Decoupling of magnetism and electric transport in single-crystal (Sr1–xAx)2IrO4 (A = Ca or Ba). United States: N. p., 2018. Web. doi:10.1088/1361-648X/aac23d.
Zhao, H. D., Terzic, Jasminka, Zheng, Hao, Ni, Y. F., Zhang, Y., Ye, Feng, Schlottmann, P., & Cao, Gang. Decoupling of magnetism and electric transport in single-crystal (Sr1–xAx)2IrO4 (A = Ca or Ba). United States. doi:https://doi.org/10.1088/1361-648X/aac23d
Zhao, H. D., Terzic, Jasminka, Zheng, Hao, Ni, Y. F., Zhang, Y., Ye, Feng, Schlottmann, P., and Cao, Gang. Mon . "Decoupling of magnetism and electric transport in single-crystal (Sr1–xAx)2IrO4 (A = Ca or Ba)". United States. doi:https://doi.org/10.1088/1361-648X/aac23d. https://www.osti.gov/servlets/purl/1465028.
@article{osti_1465028,
title = {Decoupling of magnetism and electric transport in single-crystal (Sr1–xAx)2IrO4 (A = Ca or Ba)},
author = {Zhao, H. D. and Terzic, Jasminka and Zheng, Hao and Ni, Y. F. and Zhang, Y. and Ye, Feng and Schlottmann, P. and Cao, Gang},
abstractNote = {Here, we report a systematical structural, transport and magnetic study of Ca or Ba doped Sr2IrO4 single crystals. Isoelectronically substituting Ca2+ (up to 15%) or Ba2+ (up to 4%) ion for the Sr2+ ion provides no additional charge carriers but effectively changes the lattice parameters in Sr2IrO4. In particular, 15% Ca doping considerably reduces the c-axis and the unit cell by nearly 0.45% and 1.00%, respectively. These significant, anisotropic compressions in the lattice parameters conspicuously cause no change in the Néel temperature which remains at 240 K, but drastically reduces the electrical resistivity by up to five orders of magnitude or even precipitates a sharp insulator-to-metal transition at lower temperatures, i.e. the vanishing insulating state accompanies an unchanged Néel temperature in (Sr1–xAx)2IrO4. This observation brings to light an intriguing difference between chemical pressure and applied pressure, the latter of which does suppress the long-range magnetic order in Sr2IrO4. This difference reveals the importance of the Ir1–O2–Ir1 bond angle and homogenous volume compression in determining the magnetic ground state. All results, along with a comparison drawn with results of Tb and La doped Sr2IrO4, underscore that the magnetic transition plays a nonessential role in the formation of the charge gap in the spin–orbit-tuned iridate.},
doi = {10.1088/1361-648X/aac23d},
journal = {Journal of Physics. Condensed Matter},
number = 24,
volume = 30,
place = {United States},
year = {2018},
month = {5}
}

Journal Article:
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Figures / Tables:

Fig. 1 Fig. 1: (a) The crystal structure of Sr2IrO4. Note that the lower panel illustrates the rotation of IrO6 octahedra about the $c$-axis for Sr2IrO4. (b) Representative single crystals of Ca doped Sr2IrO4.

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    Works referencing / citing this record:

    Crossover between Mott and Efros-Shklovskii variable-range hopping in Sr 2 IrO 4 epitaxial thin films by misfit strain and isovalent doping
    journal, November 2019

    • Souri, M.; Connell, J. G.; Nichols, J.
    • Journal of Applied Physics, Vol. 126, Issue 18
    • DOI: 10.1063/1.5122258

      Figures/Tables have been extracted from DOE-funded journal article accepted manuscripts.