Browsing by Author "Wu, P"

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Competition between the charge ordered and ferromagnetic states in (La,Nd)(0.75)Na0.25MnO3 manganites
(2004-05-24)
Li, ZQ
;
Zhang, XH
;
Yu, JS
;
Liu, XJ
;
Liu, XD
Structural, magnetic, and transport properties of (La1-xNdx)(0.75)Na0.25MnO3 (0 less than or equal to x less than or equal to 1) are studied. The system exhibits a rhombohedrally distorted perovskite structure for x less than or equal to 0.2 and it convert to an orthorhombic structure for x greater than or equal to 0.4. Re-entrant ferromagnetic type charge ordering transitions are observed in the narrow bandwidth samples (x greater than or equal to 0.6), while charge ordering transition is not observed for these samples with rhombohedral structure. Combining with the published results related to the charge ordering transition, we argue that the rhombohedral structure likely favor double exchange interaction and suppress charge ordering interaction. The compounds show metal to insulator transitions except Nd0.75Na0.25MnO3. The resistivity data above the metal to insulator transition temperature for the charge ordered sample are discussed in the frame work of variable-range hopping model. (C) 2004 Elsevier B.V. All rights reserved.
Novel SiO2/AlN/HfAlO/IrO2 memory with fast erase, large triangle V-th and good retention
(2005)
Lai, CH
;
Chin, A
;
Chiang, KC
;
Yoo, WJ
;
Cheng, CF
Using the strong trapping capability of novel AlN (kappa=10), low voltage drop in high-kappa layers and high workfunction IrO2 with low leakage current, the SiO2/AlN/HfAlO(K=17)/IrO2 device shows good 85 degrees C memory integrity of fast 100 is erase, large 3.7V Delta V-th and 1.9V extrapolated memory window for 10-year retention at low 13V program/erase. These increase to 5.5V Delta V-th and 3.4V for 85 degrees C 10-year retention at 1 ms erase.