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

Journal Article · · Journal of Physics. Condensed Matter
 [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)
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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.

Research Organization:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Sponsoring Organization:
USDOE
Grant/Contract Number:
AC05-00OR22725
OSTI ID:
1465028
Journal Information:
Journal of Physics. Condensed Matter, Journal Name: Journal of Physics. Condensed Matter Journal Issue: 24 Vol. 30; ISSN 0953-8984
Publisher:
IOP PublishingCopyright Statement
Country of Publication:
United States
Language:
English

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From J eff = 1 / 2 insulator to p -wave superconductor in single-crystal S r 2 I r 1 − x R u x O 4   ( 0 ≤ x ≤ 1 ) journal December 2015
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Cited By (1)

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

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Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
chemical doping
iridates
magnetism
spin–orbit coupling