Condensed-Matter Physics & Materials Science Seminar

"Suppression of weak ferromagnetism in ultrathin iridates by interfacial engineering of octahedral rotations"

Presented by Yuefeng Nie, Nanjing University, China

Thursday, September 28, 2017, 1:30 pm — ISB Bldg. 734 Conf. Rm. 201 (upstairs)

Layered iridates, Srn+1IrnO3n+1, have drawn great attention since they share remarkable similarities
with high-Tc cuprates, including layered crystalline structure, (pseudo) spin ½ states, antiferromagnetic
(AFM) Mott insulating ground state, Fermi arcs, and V shape energy gap, etc. Nonetheless, direct
evidences of superconductivity such as zero resistivity and Meissner effect are still lacking up to date.
The strong spin-orbit coupling and IrO6 octahedral rotations in 5d iridates result in a canted AFM
ground state with weak ferromagnetic moments in each IrO2 plane. Here, we propose to suppress the
weak ferromagnetism by suppressing the octahedral rotations in iridates, which may facilitate the
Cooper pairing. Using a combination of reactive molecular beam epitaxy (MBE), in situ angleresolved
photoemission spectroscopy (ARPES) and first principle calculations, we investigate the
evolution of octahedral rotations, electronic structure and magnetic ordering in ultra-thin SrIrO3 films
grown on (001) SrTiO3 substrate. Our experimental results and theoretical calculations show that
octahedral rotations and weak ferromagnetic moments are fully suppressed in 1 and 2 unit cell thick
SrIrO3 films through interfacial clamping effects.
If time allows, I will also present our recent work on the new understanding of RHEED oscillations
in the growth of oxides and the chemically specific termination control of oxide interfaces via layerby-
layer mean inner potential engineering.

Hosted by: Weiguo Yin

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