Decoupling of the Antiferromagnetic and Insulating States in Tb doped Sr2IrO4

Abstract

Sr2IrO4 is a spin-orbit coupled insulator with an antiferromagnetic (AFM) transition at TN=240 K. We report results of a comprehensive study of single-crystal Sr2Ir1-xTbxO4. This study found that mere 3% (x=0.03) tetravalent Tb4+(4f7) substituting for Ir4+ (rather than Sr2+) completely suppresses the long-range collinear AFM transition but retains the insulating state, leading to a phase diagram featuring a decoupling of magnetic interactions and charge gap. The insulating state at x=0.03 is characterized by an unusually large specific heat at low temperatures and an incommensurate magnetic state having magnetic peaks at (0.95, 0, 0) and (0, 0.95, 0) in the neutron diffraction, suggesting a spiral or spin density wave order. It is apparent that Tb doping effectively changes the relative strength of the SOI and the tetragonal CEF and enhances the Hund's rule coupling that competes with the SOI, and destabilizes the AFM state. However, the disappearance of the AFM accompanies no metallic state chiefly because an energy level mismatch for the Ir and Tb sites weakens charge carrier hopping and renders a persistent insulating state. This work highlights an unconventional correlation between the AFM and insulating states in which the magnetic transition plays no critical role in the formation of the charge gap in the iridate.

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Cited by in corpus (24)

• The Challenge of Spin-Orbit-Tuned Ground States in Iridates
• Electrical Control of Structural and Physical Properties via Strong Spin-Orbit Interactions in Sr2IrO4
• The Jeff=1/2 antiferromagnet Sr2IrO4: A golden avenue toward new physics and functions
• Correlation effects and hidden spin-orbit entangled electronic order in parent and electron-doped iridates Sr${}_2$IrO${}_4$
• Effect of Cu${}^{2+}$ substitution in Spin-Orbit Coupled Sr${}_2$Ir${}_{1-x}$Cu${}_x$O${}_4$: Structure, magnetism and electronic properties
• Possible quantum paramagnetism in compressed Sr${}_2$IrO${}_4$
• La-doping effect on spin-orbit coupled Sr2IrO4 probed by x-ray absorption spectroscopy
• Structural evolution and electronic properties of (Sr1-xCax)2-yIrO4+z spin-orbit assisted insulators
• Persistent large anisotropic magnetoresistance and insulator to metal transition in spin-orbit coupled antiferromagnets Sr2(Ir1-xGax)O4
• Pseudospin-lattice coupling and electric control of the square-lattice iridate Sr2IrO4
• Simultaneous Metal-Insulator and Antiferromagnetic Transitions in Orthorhombic Perovskite Iridate Sr0.94Ir0.78O2.68 Single Crystals
• Towards Electrical-Current Control of Quantum States in Spin-Orbit-Coupled Matter
• Nonsymmorphic Dirac semimetal and carrier dynamics in doped spin-orbit-coupled Mott insulator Sr${}_2$IrO${}_4$
• Compass Impurity Model of Tb Substitution in Sr2IrO4
• Magnetism and electrical transport in Y-doped layered iridate Sr${}_2$IrO${}_4$
• Insight into the magnetic behavior of Sr${}_2$IrO${}_4$:A spontaneous magnetization study
• Decoupling of magnetism and electric transport in single-crystal (Sr1-xAx)2IrO4 (A = Ca or Ba)
• Modeling multiorbital effects in Sr2IrO4 under strain and a Zeeman field
• Low-energy electrodynamics of Dirac semimetal phases in the doped Mott insulator Sr${}_2$IrO${}_4$
• Quantum Criticality in a Layered Iridate
• Magnetic and electronic properties of La${}_{3}M$O${}_7$ and possible polaron formation in hole-doped La${}_{3}M$O${}_7$ ($M$=Ru and Os)
• Structural origin of the Jeff=1/2 antiferromagnetic phase in Ga-doped Sr2IrO4
• Fortuitous partners of antiferromagnetic and Mott states in spin-orbit-coupled Sr2IrO4: A study of Sr2Ir1-xMxO4 (M=Fe or Co)
• A critical point in Sr2-xIrO4 and less distorted IrO6 octahedra induced by deep Sr-vacancies