Research

This section provides an overview of the research initiatives I am presently engaged in. For further information, please refer to the individual project links provided below.

Light-induced modification of the metal-to-insulator transition in CdS/LSMO heterostructures in 3 nm LSMO. Resistance versus temperature R(T) measurements for hybrid CdS/LSMO heterostructures, for (a) varying light power density and (b) varying magnetic field. The CdS/LSMO heterostructures show an enhanced conductivity, with a resistance drop of about 37%, at the transition temperature under light stimuli.

Hybrid Heterostructures for Multifunctional Materials

Engineering semiconductor/oxide heterostructures, such as, CdS/LaSrMnO3, to realize interface-driven behavior where photoexcited carrier dynamics, band offset, and Schottky barrier modulation decouple electronic conductivity from magnetic ordering. Such hybrid stacks exhibit light-tunable resistance and enable room-temperature optoelectronic control in manganites and other correlated materials.

Paper related: - H. Navarro, A. C. Basaran, F. Ajejas, L. Fratino, S. Bag, T. D. Wang, E. Qiu, V. Rouco, I. Tenreiro, F. Torres, A. Rivera-Calzada, J. Santamaria, M. Rozenberg, I. K. Schuller, Light-Induced Decoupling of Electronic and Magnetic Properties in Manganites. Physical Review Applied 19, 044077 (2023). Article Link.

Phase-Engineered Transition Metal Oxides

We design bilayer heterostructures to achieve light-triggered manipulation of metal–insulator transition pathways. The system can exhibit both volatile (reversibly) and/or non-volatile (stable) photon-induced changes in resistance via carrier injection facilitated by photons. Different transport regimes—hopping vs. activated—are realized based on light exposure and thermal cycling. The dual-mode behavior provides a means to optically control resistive states independent of ion migration or structural phase transitions.

We present a novel heterostructure approach to disentangle the mechanism of electrical transport of the strongly correlated PrNiO3 (PNO), by placing the nickelate under the photoconductor CdS. This enables the injection of carriers into PrNiO3 in a controlled way, which can be used to interrogate its intrinsic transport mechanism.

Papers related: J. Li, H. Navarro, A. Pofelski, P. Salev, R. El Hage, E. Qiu, Y. Zhu, Y. Fainman, I. K. Schuller, Laser-induced selective local patterning of vanadium oxide phases. Advanced Composites and Hybrid Materials 8, 157 (2025). Article Link.

H. Navarro, S. Das, F. Torres, R. Basak, E. Qiu, N. M. Vargas, P. N. Lapa, I. K. Schuller, A. Frano, Disentangling transport mechanisms in a correlated oxide by photoinduced charge injection. Physical Review Materials 7, L123201 (2023). Article Link.

C. Adda, H. Navarro, J. Kaur, M.-H. Lee, C. Chen, M. Rozenberg, S. P. Ong, I. K. Schuller, An optoelectronic heterostructure for neuromorphic computing: CdS/V3O5. Applied Physics Letters 121, 041901 (2022). Article Link.

H. Navarro, J. d. Valle, Y. Kalcheim, N. M. Vargas, C. Adda, M.-H. Lee, P. Lapa, A. Rivera-Calzada, I. A. Zaluzhnyy, E. Qiu, O. Shpyrko, M. Rozenberg, A. Frano, I. K. Schuller, A hybrid optoelectronic Mott insulator. Applied Physics Letters 118, 141901 (2021). Article Link.

Stochastic Switching in Correlated Oxides

We investigate the cycle-to-cycle variability in resistive switching of VOx devices at the insulator–metal transition. The electrical characterizations reveal random domain nucleation to stochastic switching voltages. The inherent variability is a key feature for achieving neuron-like firing and probabilistic computing. Our work renders VOx a platform for stochastic neuromorphic function without complex architectures.

(B) The electric field was applied between two Pt electrodes, forming a two-terminal planar device. (C) One hundred fifty voltage–current loops measured from the same device at room temperature. (D) Statistical distribution of the threshold voltage (Vth). (E) The initial resistance values (at T = 300 K) for the M1 phase VO2 for 150 cycles on the same device at room temperature.

Papers related: E. Qiu, P. Salev, F. Torres, H. Navarro, R. C. Dynes, I. K. Schuller, Stochastic transition in synchronized spiking nanooscillators. Proceedings of the National Academy of Sciences 120, e2303765120 (2023). Article Link.

E. Qiu, P. Salev, L. Fratino, R. Rocco, H. Navarro, C. Adda, J. Li, M.-H. Lee, Y. Kalcheim, M. Rozenberg, I. K. Schuller, Stochasticity in the synchronization of strongly coupled spiking oscillators. Applied Physics Letters 122, 094105 (2023). Article Link.

S. Cheng, M.-H. Lee, R. Tran, Y. Shi, X. Li, H. Navarro, C. Adda, Q. Meng, L.-Q. Chen, R. C. Dynes, S. P. Ong, I. K. Schuller, Y. Zhu, Inherent stochasticity during insulator-metal transition in VO2. Proceedings of the National Academy of Sciences 118, e2105895118 (2021). Article Link.

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