Monoclinic and correlated metal phase in VO(2) as evidence of the Mott transition: coherent phonon analysis.
In femtosecond pump-probe measurements, the appearance of coherent phonon oscillations at 4.5 and 6.0 THz indicating the rutile metal phase of VO2 does not occur simultaneously with the first-order metal-insulator transition (MIT) near 68 degrees C. The monoclinic and correlated metal (MCM) phase between the MIT and the structural phase transition (SPT) is generated by a photoassisted hole excitation, which is evidence of the Mott transition. The SPT between the MCM phase and the rutile metal phase occurs due to subsequent Joule heating. The MCM phase can be regarded as an intermediate nonequilibrium state.
Kim
Hyun-Tak
HT
IT Convergence and Components Research Laboratory, ETRI, Daejeon 305-350, Republic of Korea. htkim@etri.re.kr
Lee
Yong Wook
YW
Kim
Bong-Jun
BJ
Chae
Byung-Gyu
BG
Yun
Sun Jin
SJ
Kang
Kwang-Yong
KY
Han
Kang-Jeon
KJ
Yee
Ki-Ju
KJ
Lim
Yong-Sik
YS