title: New insights into the diverse electronic phases of a novel vanadium dioxide polymorph: a terahertz spectroscopy study.
abstract: A remarkable feature of vanadium dioxide is that it can be synthesized in a number of polymorphs. The conductivity mechanism in the metastable layered polymorph VO2(B) thin films has been investigated by terahertz time-domain spectroscopy (THz-TDS). In VO2(B), a critical temperature of 240 K marks the appearance of a non-zero Drude term in the observed complex conductivity, indicating the evolution from a pure insulating state towards a metallic state. In contrast, the THz conductivity of the well-known VO2(M1) is well fitted only by a modification of the Drude model to include backscattering. We also identified two different THz conductivity regimes separated by temperature in these two polymorphs. The electronic phase diagram is constructed, revealing that the width and onset of the metal-insulator transition in the B phase develop differently from the M1 phase.
authors.affiliation: Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore.
authors.forename: James
authors.initials: J
authors.lastname: Lourembam
authors.affiliation: 1] NUSNNI-Nanocore, National University of Singapore, Singapore 117411, Singapore [2] Department of Physics, National University of Singapore, Singapore 117542, Singapore.
authors.forename: Amar
authors.initials: A
authors.lastname: Srivastava
authors.affiliation: Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore.
authors.forename: Chan
authors.initials: C
authors.lastname: La-o-vorakiat
authors.affiliation: 1] NUSNNI-Nanocore, National University of Singapore, Singapore 117411, Singapore [2] Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore 117603.
authors.forename: H
authors.initials: H
authors.lastname: Rotella
authors.affiliation: 1] NUSNNI-Nanocore, National University of Singapore, Singapore 117411, Singapore [2] Department of Physics, National University of Singapore, Singapore 117542, Singapore [3] Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Singapore.
authors.forename: T
authors.initials: T
authors.lastname: Venkatesan
authors.affiliation: Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore.
authors.forename: Elbert E M
authors.initials: EE
authors.lastname: Chia