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MA: Fachverband Magnetismus
MA 55: Thin Films: Magnetic Anisotropy
MA 55.9: Talk
Thursday, March 23, 2017, 17:15–17:30, HSZ 101
Probing the strain induced magnetic anisotropy in CoCr2O4 with x-ray magnetic circular dichroism (XMCD) — •Cinthia Piamonteze1, Yoav William Windsor1, Sridhar Reddy Avula Venkata1, Andrea Scaramucci2,3, Jeroen A. Heuver4, Beatriz Noheda4, and Urs Staub1 — 1PSI, SLS, Villigen, Switzerland — 2Mater. Theory, ETHZ, Zürich, Switzerland — 3Lab. Scient. Devel. and Novel Mater., PSI, Villigen, Switzerland — 4Zernike Inst. Adv. Mater., Univ. Groningen, Groningen, The Netherlands
CoCr2O4 (CCO) is a spinel where Co2+ and Cr3+ occupy tetrahedral and octahedral sites, respectively. CCO is one of the few single-phase multiferroic systems exhibiting a net magnetic moment [1]. It exhibits a collinear ferrimagnetic order below 95K. Below 27K a spiral spin component appears in concomitance with a ferroelectric polarization [2]. Recently it has been shown that strain engineering can successfully control the magnetic easy axis of CCO thin films between in-plane and out-of-plane [3]. In this work we present XMCD and element specific hysteresis curves at the Co and the Cr L3,2 edges for both compressive and tensile strained 40-nm-thick films. We explain the behavior of the magnetocrystalline anisotropy using quantitative values of the orbital and spin moments of Co, obtained through sum rule analysis. We specifically show that the ratio of mL/mS along the easy axis direction is 0.24 and 0.3 for tensile and compressive strain, respectively, pointing to a large Co orbital contribution. [1] Yamasaki et al. PRL 96, 207204 (2006). [2] Y. Choi et al., PRL 102, 067601 (2009). [3] J. A. Heuver et al., PRB 92, 214429 (2015).