scholarly journals Intrinsic Complex Vacancy-Induced d0 Magnetism in Ca2Nb2O7 PLD Film

2021 ◽  
Vol 8 ◽  
Author(s):  
Linjie Wu ◽  
Yongjia Zhang ◽  
Zhongquan Nie ◽  
Ensi Cao

Introducing magnetism into the ferroelectric Ca2Nb2O7 with high Curie temperature can make it a potential multiferroic material at room temperature. Stoichiometric Ca2Nb2O7, nonstoichiometric Ca1.9Nb2O7-δ and Ca2Nb1.9O7-δ single phase films were deposited on STO (110) substrate by pulsed laser deposition under appropriate conditions. The films were characterized by XRD, FE-SEM, Element mapping and XPS. Both stoichiometric Ca2Nb2O7 and Ca1.9Nb2O7-δ films were diamagnetic in the magnetic measurement and ab initio calculations, while the Ca2Nb1.9O7-δ film with the complex vacancy of VNb+O exhibited ferromagnetic behavior at room temperature, with the saturated magnetization of 3.6 emu/cm3. Calculations on the Ca2Nb2O7 (010) surface indicate that the VNb+O can induce spin polarization on the residual O atoms around the Nb vacancies, and the system was most stable when the Nb and O vacancies were the 4th nearest-neighbored, with FM coupling energetically more stable than the AFM coupling. Our work verified experimentally and theoretically the feasibility of introducing ferromagnetism into Ca2Nb2O7 film by the intrinsic complex vacancy of VNb+O.

1998 ◽  
Vol 541 ◽  
Author(s):  
W.J. Kim ◽  
J.C. Rife ◽  
J.S. Horwitz ◽  
R.C.Y. Auyeung ◽  
D.B. Chrisey ◽  
...  

AbtractThick films of piezoelectric materials have been grown by pulsed laser deposition (PLD) for use in the development of a programmable micro-fluidic controller. ZnO and BaTiO3 (BTO) films were deposited onto various substrates, including Au/Cr coated Si, Pt/Ti coated Si, and Au/Pd coated glass microchannel plates, at substrate temperatures from room temperature to 800 °C in a background pressure of O2 from 3 to 350 mTorr. ZnO films (∼5 µm thick) were single phase and (001) oriented. BTO films, 33 µm thick, on Pt/Ti/Si were single phase and polycrystalline. To fabricate piezoelectric acoustic transducer, an array of 2 × 4 gold electrodes was deposited onto the thick BTO films through a shadow mask by PLD. The transducers were attached to a simple fluidic circuit with a 1.6 × 1.6 mm cross section and used to generate a flow velocity of 1 mm/s at an operating frequency of 50 MHz.


Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3389
Author(s):  
Simona Gabriela Greculeasa ◽  
Anda-Elena Stanciu ◽  
Aurel Leca ◽  
Andrei Kuncser ◽  
Luminita Hrib ◽  
...  

Epitaxial La0.7Sr0.3MnO3 films with different thicknesses (9–90 nm) were deposited on SrTiO3 (0 0 1) substrates by pulsed laser deposition. The films have been investigated with respect to morpho-structural, magnetic, and magneto-transport properties, which have been proven to be thickness dependent. Magnetic contributions with different switching mechanisms were evidenced, depending on the perovskite film thickness. The Curie temperature increases with the film thickness. In addition, colossal magnetoresistance effects of up to 29% above room temperature were evidenced and discussed in respect to the magnetic behavior and film thickness.


1997 ◽  
Vol 493 ◽  
Author(s):  
Adriaan C. Carter ◽  
James S. Horwitz ◽  
Douglas B. Chrisey ◽  
Jeffrey M. Pond ◽  
Steven W. Kirchoefer ◽  
...  

ABSTRACTSingle phase, (100) oriented Ba0.5Sr0.5TiO3 films have been deposited by pulsed laser deposition onto (100) LaAIO3, SrTiO3, MgO substrates. The dielectric properties of these films were measured using interdigitated capacitors as a function of DC bias and temperature at 1 MHz and as a function of DC bias at 1 to 20 GHz at room temperature. Deposited films were annealed over a temperature range of 900 to 1350 C for 1 to 8 hours to observe its effect on dielectric properties. Chemical analysis on films deposited from stoichiometric targets showed the films to be up to 6% deficient in Ba and Sr under typical PLD deposition conditions. Optimal annealing conditions and target stoichiometries for minimizing dielectric loss and maximizing tuning are discussed.


Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 131
Author(s):  
Tingting Xiao ◽  
Qi Yang ◽  
Jian Yu ◽  
Zhengwei Xiong ◽  
Weidong Wu

FePt nanoparticles (NPs) were embedded into a single-crystal MgO host by pulsed laser deposition (PLD). It was found that its phase, microstructures and physical properties were strongly dependent on annealing conditions. Annealing induced a remarkable morphology variation in order to decrease its total free energy. H2/Ar (95% Ar + 5% H2) significantly improved the L10 ordering of FePt NPs, making magnetic coercivity reach 37 KOe at room temperature. However, the samples annealing at H2/Ar, O2, and vacuum all showed the presence of iron oxide even with the coverage of MgO. MgO matrix could restrain the particles’ coalescence effectively but can hardly avoid the oxidation of Fe since it is extremely sensitive to oxygen under the high-temperature annealing process. This study demonstrated that it is essential to anneal FePt in a high-purity reducing or ultra-high vacuum atmosphere in order to eliminate the influence of oxygen.


2010 ◽  
Vol 75 ◽  
pp. 202-207
Author(s):  
Victor Ríos ◽  
Elvia Díaz-Valdés ◽  
Jorge Ricardo Aguilar ◽  
T.G. Kryshtab ◽  
Ciro Falcony

Bi-Pb-Sr-Ca-Cu-O (BPSCCO) and Bi-Pb-Sb-Sr-Ca-Cu-O (BPSSCCO) thin films were grown on MgO single crystal substrates by pulsed laser deposition. The deposition was carried out at room temperature during 90 minutes. A Nd:YAG excimer laser ( = 355 nm) with a 2 J/pulse energy density operated at 30 Hz was used. The distance between the target and substrate was kept constant at 4,5 cm. Nominal composition of the targets was Bi1,6Pb0,4Sr2Ca2Cu3O and Bi1,6Pb0,4Sb0,1Sr2Ca2Cu3OSuperconducting targets were prepared following a state solid reaction. As-grown films were annealed at different conditions. As-grown and annealed films were characterized by XRD, FTIR, and SEM. The films were prepared applying an experimental design. The relationship among deposition parameters and their effect on the formation of superconducting Bi-system crystalline phases was studied.


2004 ◽  
Vol 36 (4-6) ◽  
pp. 403-408 ◽  
Author(s):  
D. O’Mahony ◽  
F. McGee ◽  
M. Venkatesan ◽  
J.G. Lunney ◽  
J.M.D. Coey

Author(s):  
Wilmar S. Torres ◽  
Noemi R. Checca ◽  
Flávio Garcia ◽  
Alexandre Mello ◽  
Andre L. Rossi ◽  
...  

2018 ◽  
Vol 10 (45) ◽  
pp. 39032-39039 ◽  
Author(s):  
Zhou Jiang ◽  
Peng Wang ◽  
Jianpei Xing ◽  
Xue Jiang ◽  
Jijun Zhao

2014 ◽  
Vol 633 ◽  
pp. 378-381
Author(s):  
Bei Li ◽  
X.B. Liu ◽  
M. Chen ◽  
X.A. Mei

Dy-doped Bi4Ti3O12 thin films were fabricated on Pt/Ti/SiO2/Si substrates by pulsed laser deposition technique, and the structures and electrical properties of the films were investigated. XRD results indicated that all of Bi4-xDyxTi3O12 films consisted of single phase of a bismuth-layered structure with well-developed rod-like grains. The remanent polarization ( Pr ) and coercive field (Ec) of the Bi4-xDyxTi3O12 Film with x=0.75 were 25μC/cm2 and 85KV/cm , respectively.


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