Strain-induced changes of the electronic properties of B -site ordered double-perovskite Sr2CoIrO6 thin films

Abstract

B-site ordered thin films of double perovskite Sr 2 CoIrO 6 were epitaxially grown by a metal-organic aerosol deposition technique on various substrates, actuating different strain states. X-ray diffraction, transmission electron microscopy and polarized far-field Raman spectroscopy confirm the strained epitaxial growth on all used substrates. Polarization dependent Co L 2,3 X-ray absorption spectroscopy reveals a change of the magnetic easy axis of the antiferromagnetically ordered (high-spin) Co 3+ sublattice within the strain series. By reversing the applied strain direction from tensile to compressive, the easy axis changes abruptly from in-plane to out-of-plane orientation. The low-temperature magnetoresistance changes its sign respectively and is described by a combination of weak anti-localization and anisotropic magnetoresistance effects. PACS numbers: 73.50.-h,75.47.-m,75.70.-i arXiv:1801.03853v2 [cond-mat.str-el]

Electronic reconstruction and charge transfer in strained Sr$_2$CoIrO$_6$ double perovskite

“…For comparison we list also the measured cexp from Ref. [25]. Lattice constant ( Å) The other end member, SIO, exhibits a P bnm structure with an (a − a − c + ) tilt pattern in Glazer's notation [16] and a strongly reduced Ir-O-Ir bond angle of Å and c = 7.85 Å) are in good agreement with previous studies [16] with an Ir-O bond length of 2.02 Å.…”

“…the end members and vary between 0.31-0.46 µ B for Co (the latter at a STO ) and 0.14-0.13 µ B for Ir. Recent XAS measurements [25] suggest a switching of the magnetic easy axis. While our results do not show a reversal, the energy difference between the preferred [100]-magnetization direction over the [001] decreases from 85 meV to 70 meV per 40-atom u.c.…”

“…To model the growth of the double perovskite Sr 2 CoIrO 6 on different substrates used in experiment [25] we have strained the lateral lattice constant to the pseudocubic one of NdGaO 3 (NGO), a NGO = 3.865 Å, SrTiO 3 (STO), a STO = 3.905 Å, and GdScO 3 (GSO), a GSO = 3.965 Å, which corresponds to compressive strain, unstrained case and tensile strain, respectively. As expected, with increasing lateral lattice constant the optimized c-parameter decreases from 7.99 Å (a NGO ) to 7.91 Å (a STO ) and, finally, 7.74 Å (a GSO ), in close agreement with the measured values [25]. The bond angles exhibit values between those of SCO and the strongly distorted SIO: while the in-plane Co-O-Ir angle increases with a from 158 • to 160 • , the out-of-plane angle decreases from 165 • to 162 • .…”

“…Previous reports on the bulk double perovskite SCIO [23][24][25][26] suggested an Ir 5+ , Co 3+ configuration, though there is a controversy on the magnetic state of Ir [24,26]: While the former study reports a nearly quenched Ir total magnetic moment of 0.039 µ B , the latter proposes the presence of a small fraction (∼ 10 %) of Ir 6+ (s = 3/2) to explain a finite Ir magnetic moment. Recently, thin films of SCIO were grown on different substrates using metalorganic aerosol deposition (MAD) [25]. Polarization-dependent x-ray absorption (XAS) measurements point towards strain dependent changes in the orbital configuration and magnetocrystalline anisotropy.…”

Polaronic Emergent Phases in Manganite-based Heterostructures

“…Moreover, B-site ordered double perovskite films, e.g., RE 2 CoMnO 6 (RE = La, Pr, Nd, etc. ), with perfect crystallinity and a high degree of B-site ordering~98% were obtained [48][49][50]. In addition, we have demonstrated the growth of intrinsically layered Ruddlesden-Popper heterostructures, e.g., SrO(SrTiO 3 ) n (n = 1-4), by means of the atomic layer epitaxy [28,29] (ALE); this type of growth has been realized earlier only by means of MBE [51].…”