Dresden 2020 – scientific programme

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MA: Fachverband Magnetismus

MA 33: Correlation Theory I

MA 33.1: Talk

Wednesday, March 18, 2020, 09:30–09:45, HSZ 403

Electronic and magnetic state of LMO/STO heterostructures: Effect of local correlation and nonlocal exchange — •Hrishit Banerjee¹, Oleg Janson², Karsten Held³, Tanusri Saha-Dasgupta⁴, and Markus Aichhorn¹ — ¹TU Graz, Austria — ²IFW Dresden, Germany — ³TU Wien, Austria. — ⁴S. N. Bose National Centre for Basic Sciences, Kolkata, India

Motivated by the puzzling report of a ferromagnetic insulating state in LaMnO₃ (LMO)/SrTiO₃ (STO) heterostructures, we calculate the electronic and magnetic state of LMO, strained to a STO square substrate. We use 3 different computational approaches: (a) DFT+U, (b) DFT + DMFT, and (c) DFT + HF as a hybrid functional. While the first two approaches include local correlations and exchange at Mn sites, treated in a static and dynamic manner, respectively, the last one takes into account the effect of nonlocal exchange at all sites. We find in all 3 approaches that compressive strain induced by square substrate of STO turns LMO to a ferromagnet with suppressed Jahn-Teller distortion, in agreement with experiment. The hybrid calculations result in a ferromagnetic insulating solution, found to arise from an electronic charge disproportionation. When correlations are included through DMFT, first a paramagnetic insulating and then on inclusion of magnetism, a ferromagnetic insulating state is observed for strained LMO. Our conclusions remain valid when we investigate LMO/STO within the experimental setup of a superlattice geometry using hybrid functionals. DMFT calculations show the presence of a paramagnetic insulating state. Ref.: Phys. Rev. B 100, 115143 (2019)