【Date and Time】16-June-2026 2pm (Beijing time)

【Venue】Room 526

【Host】 Panagiotis Kotetes (BAQIS)

【Title】Nonlinear Transport Signatures of Quantum Geometry

【Speaker】 Maria Teresa Mercaldo is an Associate Professor of Condensed Matter Physics at the University of Salerno, Italy. Her research focuses on superconductivity and quantum materials, particularly on the role of orbital degrees of freedom, topology, and quantum geometry in electronic transport properties. She collaborates with several international research groups and participates in European and bilateral projects on superconductivity, quantum materials, and nonlinear transport effects. Her research has been published in leading peer-reviewed journals, including Science, Nature, Nature Materials, and Physical Review Letters. She has delivered invited talks at major international conferences in condensed matter physics, magnetism, superconductivity, and spintronics.

【Abstract】Quantum materials exhibit remarkable physical phenomena originating from the geometry and topology of the electronic wavefunctions. These properties are encoded in the quantum geometric tensor, whose imaginary and real parts correspond to the Berry curvature and the quantum metric, respectively. While the Berry curvature is widely recognized as the origin of fundamental linear response phenomena — including the anomalous and quantum Hall effects, orbital magnetism, and electric polarization — the role of the quantum metric has only recently emerged as a central topic in condensed matter physics. In this talk, I will discuss nonlinear transport phenomena governed by quantum geometry in spin-orbit-coupled materials and oxide interfaces. I will show how spin-momentum locking generates a finite quantum metric that activates nonlinear in-plane magnetoresistance in (111)-oriented LaAlO₃/SrTiO₃ interfaces [1]. I will also address intrinsic quantum-metric contributions to nonlinear magnetoconductivity in topological-insulator surface states [2], recently observed in Sb₂Te₃ [3]. Finally, I will discuss orbital-driven Berry-curvature hot spots and giant Berry-curvature dipoles in low-symmetry quantum materials [4], highlighting their relevance to the nonlinear Hall effect observed in (111) LaAlO₃/SrTiO₃ interfaces [5].

References:

[1] G. Sala, M. T. Mercaldo, K. Domi, et al., The quantum metric of electrons with spin-momentum locking, Science 389, 822 (2025).

[2] M. T. Mercaldo, M. Cuoco, C. Ortix, Nonlinear planar magnetotransport as a probe of the topology of surface states, Phys. Rev. B 111, 155442 (2025).

[3] G. Sala, E. Longo, M. T. Mercaldo, et al., Probing the quantum metric of 3D topological insulators, Nature Materials (2026). https://doi.org/10.1038/s41563-026-02617-3.

[4] M. T. Mercaldo, C. Noce, A. Caviglia, M. Cuoco, C. Ortix, Orbital design of Berry curvature: pinch points and giant dipoles induced by crystal fields, npj Quantum Mater. 8, 12 (2023).

[5] E. Lesne, Y.G. Sa?lam, R. Battilomo, M. T. Mercaldo, et al., Designing spin and orbital sources of Berry curvature at oxide interfaces, Nature Materials 22, 576 (2023).