Oxide interfaces: a versatile platform for material design and ultrafast light control - A.D. Caviglia Kavli, Institute of Nanoscience, Delft University of Technology

11.06.2021 09:00 – 09:45

Oxide interfaces: a versatile platform for material design and ultrafast light control
A.D. Caviglia
Kavli Institute of Nanoscience, Delft University of Technology, The Netherlands

Exerting control over quantum materials is one of the main goals in condensed matter physics. Oxide interfaces have emerged as a versatile platform for material design, where new fundamental properties can be generated by assembling condensed matter at the atomic scale. Light plays a pivotal role in this scientific exploration. Probing materials with light reveals the collective excitations and the energy landscapes that underpin correlated dynamics. Recently we have come to the realisation that light not only reveals the organisation of condensed matter, it can also unlock new properties and promote phase transitions. The overarching goal of the field is to control macroscopic material properties, paving the way to new scientific insights and future emerging technologies. We will discuss three examples of material design at oxide interfaces, focusing on the control of geometric phases, superconductivity and magnetism.

In the first example we will discuss the manipulation of topological charges at oxide interfaces. Three-dimensional strontium ruthenate (SrRuO3) is an itinerant ferromagnet that features Weyl points acting as sources of emergent magnetic fields, anomalous Hall conductivity, and unconventional spin dynamics. Integrating SrRuO3 in oxide heterostructures is potentially a novel route to engineer emergent electrodynamics, but its electronic band topology in the two-dimensional limit remains unknown. We will show that ultrathin SrRuO3 exhibits spin-polarized topologically nontrivial bands at the Fermi energy. Their band anticrossings show an enhanced Berry curvature and act as competing sources of emergent magnetic fields. We control their balance by designing heterostructures with symmetric and asymmetric interfaces [1,2].

In the second example we will discuss manipulating two-dimensional, dilute superconductivity in SrTiO3-based heterostructures. We explore the gate-controlled superfluid density of the two-dimensional electron system at the LaAlO3/SrTiO3 interface by monitoring (i) the frequencies of the cavity modes of coplanar waveguide resonators [3] and (ii) the kinetic inductance of superconducting quantum interference devices [4,5] both fabricated in the interface itself. The extremely low superfluid density observed allows us to fabricate electrostatically-controlled Josephson junctions and one-dimensional channels in which the supercurrent is carried by a single quantized mode [6].

Finally, we will consider the control of magnetic ordered states using light. We will show that light-driven phonons can be utilized to coherently manipulate macroscopic magnetic states. Intense mid-infrared electric field pulses, tuned to resonance with a phonon mode of the antiferromagnet DyFeO3, induce ultrafast and long-living changes of the fundamental exchange interaction between rare-earth orbitals and transition metal spins. Non-thermal lattice control of the magnetic exchange, which defines the stability of the macroscopic magnetic state, allows us to perform picosecond coherent switching between competing antiferromagnetic and weakly ferromagnetic spin orders [7-9].

[1] D.J. Groenendijk, C. Autieri, J. Girovsky, M. Carmen Martinez-Velarte, N. Manca, G. Mattoni, A.M.R.V.L. Monteiro, N. Gauquelin, J. Verbeeck, A.F. Otte, M. Gabay, S. Picozzi, A.D. Caviglia, Spin-orbit semimetal SrIrO3 in the two-dimensional limit, Physical Review Letters 119, 256403 (2017).
[2] D. J. Groenendijk, C. Autieri, T. C. van Thiel, W. Brzezicki, N. Gauquelin, P. Barone, K. H. W. van den Bos, S. van Aert, J. Verbeeck, A. Filippetti, S. Picozzi, M. Cuoco and A. D. Caviglia, Berry phase engineering at oxide interfaces, Physical Review Research 2, 023404 (2020).
[3] N. Manca, D. Bothner, A. M. R. V. L. Monteiro, D. Davidovikj, Y. G. Sağlam, M. Jenkins, M. Gabay, G. Steele, A. D. Caviglia, Bimodal Phase Diagram of the Superfluid Density in LaAlO3/SrTiO3 Revealed by an Interfacial Waveguide Resonator, Physical Review Letters 122, 036801 (2019).
[4] A.M.R.V.L. Monteiro, D.J. Groenendijk, N. Manca, E. Mulazimoglu, S. Goswami, Ya. Blanter, L.M.K. Vandersypen, A.D. Caviglia, Side gate tunable Josephson junctions at the LaAlO3/SrTiO3 interface, Nano Letters 17, 715 (2017).
[5] S. Goswami, E. Mulazimoglu, A.M.R.V.L. Monteiro, R.Wölbing, D. Koelle, R. Kleiner, Y. M. Blanter, L.M.K. Vandersypen, A.D. Caviglia, Quantum interference in an interfacial superconductor, Nature Nanotechnology 11, 861 (2016).
[6] H. Thierschmann, E. Mulazimoglu, N. Manca, S. Goswami, T.M. Klapwijk, A.D. Caviglia, Superconducting quantum point contact with split gates in the two dimensional LaAlO3/SrTiO3 superfluid, Nature Communications 9, 2276 (2018).
[7] J.R. Hortensius, D. Afanasiev, A. Sasani, E. Bousquet, A.D. Caviglia, Tunable shear strain from resonantly driven optical phonons, npj Quantum Materials 5, 95 (2020).
[8] D. Afanasiev, J.R. Hortensius, B.A. Ivanov, A. Sasani, E. Bousquet, Y.M. Blanter, R.V. Mikhaylovskiy, A.V. Kimel, A.D. Caviglia, Ultrafast control of magnetic interactions via light-driven phonons, Nature Materials 20, 607 (2021).
[9] D. Afanasiev, J.R. Hortensius, M. Matthiesen, S. Mañas-Valero, M. Šiškins, M. Lee, E. Lesne, P.G. Steeneken, B.A. Ivanov, E. Coronado, A.D. Caviglia Controlling the anisotropy of a van der Waals antiferromagnet with light, Science Advances (2021).

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