Author:
Hwang In-Hui,Park Chang-In,Yeo Sunmog,Sun Cheng-Jun,Han Sang-Wook
Abstract
AbstractVO2 is a highly correlated electron system which has a metal-to-insulator transition (MIT) with a dramatic change of conductivity accompanied by a first-order structural phase transition (SPT) near room temperature. The origin of the MIT is still controversial and there is ongoing debate over whether an SPT induces the MIT and whether the Tc can be engineered using artificial parameters. We examined the electrical and local structural properties of Cr- and Co-ion implanted VO2 (Cr-VO2 and Co-VO2) films using temperature-dependent resistance and X-ray absorption fine structure (XAFS) measurements at the V K edge. The temperature-dependent electrical resistance measurements of both Cr-VO2 and Co-VO2 films showed sharp MIT features. The Tc values of the Cr-VO2 and Co-VO2 films first decreased and then increased relative to that of pristine VO2 as the ion flux was increased. The pre-edge peak of the V K edge from the Cr-VO2 films with a Cr ion flux ≥ 1013 ions/cm2 showed no temperature-dependent behavior, implying no changes in the local density of states of V 3d t2g and eg orbitals during MIT. Extended XAFS (EXAFS) revealed that implanted Cr and Co ions and their tracks caused a substantial amount of structural disorder and distortion at both vanadium and oxygen sites. The resistance and XAFS measurements revealed that VO2 experiences a sharp MIT when the distance of V–V pairs undergoes an SPT without any transitions in either the VO6 octahedrons or the V 3d t2g and eg states. This indicates that the MIT of VO2 occurs with no changes of the crystal fields.
Funder
National Research Foundation of Korea government grant funded by the Ministry of Education
The research funds of Jeonbuk National University in 2019
Publisher
Springer Science and Business Media LLC
Reference62 articles.
1. Morine, F. J. Oxides which show a metal-to-insulator transition at the Neel temperature. Phys. Rev. Lett. 3, 34 (1959).
2. Goodenough, J. B. The two components of the crystallographic transition in VO2. J. Solid State Chem. 3, 490 (1971).
3. Eyert, V. The metal-insulator transitions of VO2: a band theoretical approach, Ann. Phys. (Leipzig) 11, 650 (2002).
4. Yang, Z. et al. Oxide electronics utilizing ultrafast metal-insulator transitions. Ann. Rev. Mater. Res. 41, 337 (2011).
5. Qazilbash, M. M. et al. Basov, Mott transition in VO2 revealed by infrared spectroscopy and nano-imaging. Science 318, 1750 (2007).
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