Browsing by Author "Wang, L. M."

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Characterization of the charge density wave transition and observation of the amplitude mode in LaAuSb2
(2019-06-10)
Kuo, C. N.
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Shen, D.
;
Li, B. S.
;
Nguyen Nhat Quyen
;
Tzeng, W. Y.
In order to elucidate the charge density wave (CDW) nature in LaAuSb2, we have carried out the electrical resistivity, Hall coefficient, Seebeck coefficient, thermal conductivity, as well as ultrafast pump-probe spectroscopy measurements on single crystalline LaAuSb2. The CDW phase transition has been characterized by marked features near T-C similar or equal to 88 K. In particular, the obtained Hall carrier concentration and electronic thermal conductivity exhibit significant reduction as T-C drops, providing strong evidence for partial gapping of the Fermi surfaces during the CDW phase transition. Furthermore, the ultrafast pump-probe spectroscopy reveals pronounced oscillatory features in the photoinduced transient reflectivity in the CDW ordered state. A characteristic oscillation mode with frequency of about 0.32 THz was extracted. The comparison of the obtained oscillation frequency with the frequencies of the amplitude mode in the well-studied CDW analogue LaAgSb2 allows us to ascribe the observation to the amplitude mode of CDW collective excitations in LaAuSb2.
Optical and magneto-optical studies of (La(0.7)A(0.3))MnO(3) (A = Sr, Ca, and Ce) thin films
(2006-09-01)
Liu, H. L.
;
Zhang, Kenneth Y. -J.
;
Wu, L. C.
;
Uba, L.
;
Uba, S.
The optical and magneto-optical (MO) properties of (La(0.7)A(0.3))MnO(3) (A = Sr, Ca, and Ce) thin films have been investigated. It is found that the value shape of spectra is strongly dependent on different cation dopings. The Sr-doped thin film exhibits a strong Drude response and maximum Kerr rotation angle of 0.32 degrees at similar to 3.4 eV. Interestingly, the replacement of Sr ions with the smaller Ca ions and the tetravalent Ce ions all lead to a remarkable suppression of the carrier density and the MO response. Such differences are interpreted as due to their different electronic band structures. (C) 2006 Elsevier B.V. All rights reserved.