skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Correlation between antiferromagnetic and Mott states in spin orbit coupled Sr 2 Ir O 4 : A study of Sr 2 Ir 1 x M x O 4 ( M = Fe or Co)

Journal Article · · Physical Review B

Sr2IrO4 is an archetypal spin-orbit-coupled Mott insulator with an antiferromagnetic state below 240 K. Here we report results of our study on single crystals of Sr2Ir1–xFexO4 (0 ≤ x < 0.32) and Sr2Ir1–xCoxO4 (0 ≤ x < 0.22). Fe doping retains the antiferromagnetic state but simultaneously precipitates an emergent metallic state whereas Co doping causes a rapid collapse of both the antiferromagnetic and Mott states, giving rise to a confined metallic state featuring a pronounced linearity of the basal-plane resistivity up to 700 K. The results indicate tetravalent Fe4+ (3d4) ions in the intermediate spin state with S = 1 and Co4+ (3d5) ions in the high spin state with S = 5/2 substituting for Ir4+ (5d5) ions in Sr2IrO4, respectively. The effective magnetic moment closely tracks the Néel temperature as doping increases, suggesting that the spin state of the dopant predominately determines the magnetic properties in doped Sr2IrO4. Furthermore, all relevant properties including charge-carrier density (e.g., 1028/m3), Sommerfeld coefficient (e.g., 19 mJ / mole K2), and Wilson ratio (e.g., 2.6) consistently demonstrate an emergent metallic state that is both robust and highly correlated in the two systems, arising from the percolation of bound states and the weakening of structural distortions. Furthermore, this study strongly indicates that the antiferromagnetic and Mott states are correlated in an unconventional manner in Sr2IrO4.

Research Organization:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Organization:
USDOE; National Science Foundation (NSF)
Grant/Contract Number:
AC05-00OR22725; DMR-1903888
OSTI ID:
1819586
Journal Information:
Physical Review B, Vol. 103, Issue 11; ISSN 2469-9950
Publisher:
American Physical Society (APS)Copyright Statement
Country of Publication:
United States
Language:
English

References (49)

X-ray Absorption Spectroscopy Study of the Effect of Rh doping in Sr2IrO4 journal March 2016
Spin-orbit tuned metal-insulator transitions in single-crystal Sr 2 Ir 1 x Rh x O 4 ( 0 x 1 ) journal September 2012
Novel metallic ferromagnet Sr2CoO4 journal August 2005
Superconductivity in doped Sr 2 IrO 4 : A functional renormalization group study journal March 2014
Structural and magnetic studies of Sr 2 IrO 4 journal April 1994
Lattice-driven magnetoresistivity and metal-insulator transition in single-layered iridates journal September 2011
Correlated Quantum Phenomena in the Strong Spin-Orbit Regime journal March 2014
Pseudospin-lattice coupling and electric control of the square-lattice iridate Sr 2 Ir O 4 journal September 2020
Evidence of an odd-parity hidden order in a spin–orbit coupled correlated iridate journal October 2015
Interlayer pair hopping: Superconductivity from the resonating-valence-bond state journal April 1988
Coulomb correlations in 4d and 5d oxides from first principles—or how spin–orbit materials choose their effective orbital degeneracies journal May 2017
Structure symmetry determination and magnetic evolution in Sr 2 Ir 1 x Rh x O 4 journal November 2015
Large linear-in-temperature resistivity in twisted bilayer graphene journal August 2019
Structural Distortion-Induced Magnetoelastic Locking in Sr 2 IrO 4 Revealed through Nonlinear Optical Harmonic Generation journal March 2015
Possible Quantum Paramagnetism in Compressed Sr 2 IrO 4 journal February 2020
Phase-Sensitive Observation of a Spin-Orbital Mott State in Sr2IrO4 journal March 2009
Dimensionality-controlled Mott transition and correlation effects in single-layer and bilayer perovskite iridates journal June 2013
Evolution of competing magnetic order in the J eff = 1 / 2 insulating state of Sr 2 Ir 1 x Ru x O 4 journal October 2015
Observation of a d-wave gap in electron-doped Sr2IrO4 journal October 2015
Magnetic structural change of Sr 2 IrO 4 upon Mn doping journal December 2012
Monte Carlo Study of an Unconventional Superconducting Phase in Iridium Oxide J eff = 1 / 2 Mott Insulators Induced by Carrier Doping journal January 2013
Pressure Tuning of the Spin-Orbit Coupled Ground State in Sr 2 IrO 4 journal July 2012
Neutron Powder Diffraction Study of the Crystal Structures of Sr2RuO4 and Sr2IrO4 at Room Temperature and at 10 K journal October 1994
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
Odd-parity superconductivity driven by octahedra rotations in iridium oxides journal August 2019
Spin-Orbit Physics Giving Rise to Novel Phases in Correlated Systems: Iridates and Related Materials journal March 2016
Odd-Parity Triplet Superconducting Phase in Multiorbital Materials with a Strong Spin-Orbit Coupling: Application to Doped Sr 2 IrO 4 journal October 2014
Decoupling of the antiferromagnetic and insulating states in Tb-doped S r 2 Ir O 4 journal December 2015
Why the temperature is high journal July 2004
Novel J eff = 1 / 2 Mott State Induced by Relativistic Spin-Orbit Coupling in Sr 2 IrO 4 journal August 2008
Magnetic and crystal structures of Sr 2 IrO 4 : A neutron diffraction study journal April 2013
Metal-insulator transition in dirty Kondo insulators journal January 1996
Hallmarks of the Mott-metal crossover in the hole-doped pseudospin-1/2 Mott insulator Sr2IrO4 journal April 2016
Weak ferromagnetism, metal-to-nonmetal transition, and negative differential resistivity in single-crystal Sr 2 IrO 4 journal May 1998
Local density of states study of a spin-orbit-coupling induced Mott insulator Sr 2 Ir O 4 journal July 2014
Persistent insulating state at megabar pressures in strongly spin-orbit coupled S r 2 Ir O 4 journal April 2020
Recent progress on correlated electron systems with strong spin–orbit coupling journal August 2016
Two-Dimensional Heisenberg Behavior of J eff = 1 / 2 Isospins in the Paramagnetic State of the Spin-Orbital Mott Insulator Sr 2 IrO 4 journal June 2012
Superconductivity in Bad Metals journal April 1995
The challenge of spin–orbit-tuned ground states in iridates: a key issues review journal February 2018
Twisted Hubbard Model for Sr 2 IrO 4 : Magnetism and Possible High Temperature Superconductivity journal March 2011
Dilute magnetism and spin-orbital percolation effects in Sr 2 Ir 1 x Rh x O 4 journal February 2014
Pressure-Induced Confined Metal from the Mott Insulator Sr 3 Ir 2 O 7 journal May 2016
‘Confined coherence’ in strongly correlated anisotropic metals journal December 1997
Localized-to-itinerant electron transition in Sr 2 Ir 1 x Ru x O 4 journal May 1994
Influence of electron doping on the ground state of ( Sr 1 x La x ) 2 IrO 4 journal August 2015
Sr 2 Ir 1 x Rh x O 4 ( x < 0.5 ) : An inhomogeneous j eff = 1 2 Hubbard system journal August 2015
Mott Insulators in the Strong Spin-Orbit Coupling Limit: From Heisenberg to a Quantum Compass and Kitaev Models journal January 2009
Synthesis and characterization of Sr2Ir1−xMxO4 (M=Ti, Fe, Co) solid solutions journal June 2012