Draft:Joseph Falson

Joseph Falson
Joseph L. Falson
Born	Joseph L. Falson New South Wales, Australia
Education	University of New South Wales (BS) Tohoku University (MS) University of Tokyo (PhD)
Scientific career
Fields	Materials science Condensed matter physics Cryogenics Thin films
Institutions	Max Planck Institute for Solid State Research California Institute of Technology
Academic advisors	Masashi Kawasaki Klaus von Klitzing

Joseph L. Falson is an Australian-American materials scientist and expert in highly crystalline materials and molecular beam epitaxy. Falson is an assistant professor of Materials Science and William H. Hurt Scholar at the California Institute of Technology (Caltech).

Falson is known for his discovery of a two-dimensional superconducting material that defies conventional theories by retaining its superconductivity under strong magnetic fields.

Biography

Early life and education

Falson was born in Australia and raised in Port Macquarie, New South Wales, where he developed an interest in the physical properties of materials during his early education. He pursued this interest at the University of New South Wales, where he completed his undergraduate studies in chemistry. He then travelled internationally, where he earned a MSc degree from Tohoku University before earning a scholarship from the Japanese government to conduct research at the University of Tokyo under Masashi Kawasaki. There, he studied crystal growth and condensed matter physics and earned his PhD in materials science.

Following his doctoral work, Falson continued his studies in Germany at the Max Planck Institute for Solid State Research where he researched low-temperature transport with Jürgen Smet and Klaus von Klitzing before eventually joining Caltech as an assistant professor in 2020.

Research

Falson's research is rooted in the study of quantum mechanical ground states within highly crystalline materials, a branch in condensed matter science that seeks to understand the principles of emergence and topology. Falson's approach is to design novel materials from the ground up, aiming to create platforms that are experimentally accessible and demonstrate unique electrical, optical, and thermal phenomena. The primary technique he employs is thin-film epitaxy, a process of depositing single-atomic layers of material onto crystalline substrates to build high-quality crystals with minimal defects. His laboratory specializes in using molecular beam epitaxy, a method that evaporates elements in a vacuum to form a beam that condenses on a substrate, constructing complex layered crystals on an atomic scale.

The materials synthesized in Falson's lab are often studied under extreme conditions—high magnetic fields, high pressures, and very low temperatures—to discern their chemical, structural, electronic, and optical properties. By custom-designing experimental apparatus, his lab extracts detailed thermodynamic data from these materials, which in turn informs and refines the growth process to enhance the quality of the crystals produced.

A significant focus of Falson's research is on the phenomenon of superconductivity, particularly in materials that maintain superconducting properties under conditions that traditionally disrupt this state. His work involves synthesizing new materials with potential novel electronic properties and improving known materials, including ultrathin films and exotic superconductors. In collaboration with researchers from Tsinghua University and the Max Planck Institute for Solid State Research, Falson discovered a superconducting material that defied traditional theoretical expectations by retaining superconductivity even in strong magnetic fields.

This breakthrough study revolved around a material composed of layered crystals, including bismuth telluride and lead telluride, topped with a thin layer of gray tin, which at minimal thickness behaves two-dimensionally, confining electron movement to a plane. The research revealed that the material's superconductivity was unusually resilient to magnetic fields, a finding that challenges conventional theories and suggests a structural property of the layered material that prevents easy alignment of electron spins with an applied magnetic field.

Falson's laboratory recently has pushed to explore the quantum properties of electrons, particularly their spin in superconducting materials, and how these properties interact with the material's electronic structure. He aims to advance the fundamental understanding of superconductivity but also contribute to the quest for materials capable of superconducting at room temperature, which could have profound implications for energy transmission and electronic devices.

Selected publications

• Falson, J., Xu, Y., Liao, M., Zang, Y., Zhu, K., Wang, C., Zhang, Z., Liu, H., Duan, W., He, K. and Liu, H., 2020. Type-II Ising pairing in few-layer stanene. Science, 367(6485), pp.1454-1457.
• Falson, J., Sodemann, I., Skinner, B., Tabrea, D., Kozuka, Y., Tsukazaki, A., Kawasaki, M., von Klitzing, K. and Smet, J.H., 2022. Competing correlated states around the zero-field Wigner crystallization transition of electrons in two dimensions. Nature materials, 21(3), pp.311-316.
• Falson, J. and Kawasaki, M., 2018. A review of the quantum Hall effects in MgZnO/ZnO heterostructures. Reports on Progress in Physics, 81(5), p.056501.
• Falson, J., Kozuka, Y., Uchida, M., Smet, J.H., Arima, T.H., Tsukazaki, A. and Kawasaki, M., 2016. MgZnO/ZnO heterostructures with electron mobility exceeding 1× 106 cm2/Vs. Scientific reports, 6(1), p.26598.
• Falson, J., 2023. A highly anisotropic polymorph. Nature Physics, 19(1), pp.19-20.
• Falson, J., Maryenko, D., Kozuka, Y., Tsukazaki, A. and Kawasaki, M., 2011. Magnesium doping controlled density and mobility of two-dimensional electron gas in MgxZn1-xO/ZnO heterostructures. Applied physics express, 4(9), p.091101.
• Llanos, A., Salmani-Rezaie, S., Kim, J., Kioussis, N., Muller, D.A. and Falson, J., 2023. Supercell formation in epitaxial rare-earth ditelluride thin films. Crystal Growth & Design, 24(1), pp.115-121.

References

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