Structure, magnetism, and transport properties for Ca doping in Sr2IrO4

Abstract

An immediate quenching using liquid N2 is applied for synthesizing the 5d transition-metal oxides (Sr1-xCax)2IrO4 (0 ≤ x ≤ 0.15) single phase. X-ray diffraction together with Rietveld refinement shows that the lattice parameters along a and c directions and the bond angle of Ir-O2-Ir decrease with the increase of Ca content. X-ray Absorption Fine Spectroscopy measurements prove that the valence of Ir and the average Ir-O bond-length substantially remain unchanged with Ca content increasing in the phase. The effective magnetic moment μeff and Néel temperature TN decrease simultaneously with increased Ca content. Electrical resistivity shows complex temperature dependence behavior, which follows the three-dimensional variable range hopping behavior at low temperature, Arrhenius-type behavior at middle-temperature, and a weak electronic localization in quasi-two-dimensional at high temperature.

Magnetic phase diagram of Sr2−xLaxIrO4 synth

“…In this theoretical calculation, the suppression of T N by c/a can be explained by the decreased exchange coupling of J. Similar T N vs c/a trends have been observed experimentally in Ca doping [19] and Tb doping [20]. These results suggest that the magnetism of a Sr214 system is strongly correlated with the parameters of its crystal structure, such as c/a.…”

“…The La dependence of T N in our results favorably Temperature dependence of the (a,b) magnetic susceptibility in Sr 2−x La x IrO 4 .T NRelationship between the tetragonal distortion c/a and magnetic transition temperature T N in Sr214 systems. The Ca-and Tb-doping results were obtained from Refs [19,20]…”

First-principles calculation of spin and orbital contributions to magnetically ordered moments in Sr2IrO4

“…Our electronic structure is also in reasonable accord with with resonant inelastic x-ray scattering observations and a 3band tight-binding model fit to experimental optical conductivity and ARPES. [66][67][68] Due to the indirect nature of the band gap, the gap in the DOS is only 55 meV, in agreement with electronic transport measurements [69,70]. The opening of the band gap is typically ascribed to moderate on-site electron-electron interactions originating in a half-filled J ef f = 1/2 band.…”

Nonlocal Coulomb correlations in pure and electron-doped Sr2IrO4 : Spectral functions, Fermi surface, and pseudo-gap-like spectral weight distributions from oriented cluster dynamical mean-field theory

“…As in the cuprates, stoechiometric samples of Sr 2 IrO 4 are insulating as a result of Coulomb interaction effects beyond the single-particle band picture, and at low temperatures antiferromagnetic order sets in [6]. The phase diagram has been explored extensively both, using different theoretical methods [4,5,[7][8][9][10][11][12][13][14][15][16][17][18] and by various experimental probes: optics [2,[19][20][21][22][23][24], photoemission [2,17,[25][26][27][28][29][30][31][32][33][34], transport [3,[35][36][37][38][39][40], scanning tunneling microscopy and spectroscopy experiments [41,42], and X-ray spectroscopy [43][44][45][46][47] have contributed to establish the picture of an insulator with a s...…”