We investigated the evolution of the magnetic behavior of Sr3Ir2O7 under pressure using Resonant Elastic X-Ray Scattering (REXS) on I16, the beamline for materials and magnetism at Diamond Light Source [1]. This compound is the n = 2 case of the Ruddlesden-Popper (RP) series of layered perovskites Srn+1IrnO3n+1 that presents tetragonal structure at ambient conditions (I4/mmm, a = 3.9026 Å, c = 20.9300 Å).
In this series of layered perovskites, the interplay between the crystal field, the on-site Coulomb repulsion (U) and the increasing bandwidth (W) from n = 1 to n = ∞, give rise to a rich landscape of fascinating behaviors from the Mott-insulating Sr2Ir04 (n = 1) [3], to the fully metallic SrIrO3 (n = ∞) [4]. Sr3Ir2O7 (n = 2), presents a weak insulating behavior and antiferromagnetic order, with k = (0.5,0.5,0) and moments along the c-axis, below 285 K at ambient pressure. Pressure is an ideal tool to explore the natural tendency of the transition metal oxygen octaedra in this kind of structures to rotate and distort, giving rise to potential alterations in the strength and sign of the mangetic interactions. In fact, the effect of chemical pressure by dopping the Sr sites with La in the (Sr1-xLax)Ir2O7 has shown to be the lead to a very rich phase diagram of electronic behaviours [5].
Thanks to the recently developed high-pressure capability on I16 [6] we measured magnetic reflections (see fig. 1) up to 12 GPa tuning the photon energy through the Ir-L3 absorption edge. A preliminary analysis of the collected data suggest a linear decrease of TN mirroring what observed under chemical substitution. The models qualitatively consistent with this trend will be discussed.
Acknowledgments: We would like to acknowledge the support provided by Mr. David McCabe, Mr. Robert Pocock and the I15 and I19 beamlines at Diamond. This work was done under the studentship STU0076-CT-1049 co-funded by The University of Edinburgh and Diamond Light Source. We aknowleadge Diamond Light Source for the beamtimes allocated under proposals MT17731-1, MT19890-1 and MT20778-1.
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[6] I. Povedano et al. (to be published).