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91.
《Current Opinion in Solid State & Materials Science》2014,18(1):6-18
Very recently, vertically aligned nanocomposite (VAN) thin films have served as an intriguing platform to obtain significant insights of the fundamental physics and achieve novel functionalities for potential technological applications. In this review article, we have investigated the lattice mismatch and vertical interfacial coupling in representative VAN systems for probing strain engineering in the vertical direction. Systematic studies of ferroelectricity, low field magnetoresistance and magnetoelectric coupling in VAN architectures have been reviewed and compared. The enhancement and tunability of the physical properties are attributed to the effective strain-, phase- and interface- couplings in VAN films. In the end, important and promising research directions in this field are proposed, including understanding the growth mechanisms of VAN structures, and creating more effective couplings for enhanced functionalities and ultimate device applications. 相似文献
92.
In the present work, the AC magnetoimpedance effect in La0.7Ca0.3MnO3−δ at various temperatures are investigated. The peak of the metal–insulator transition occurs in the temperature dependence of impedance. Negative magnetoimpedance effect in the La0.7Ca0.3MnO3−δ is obtained at frequencies f≤10 MHz. In the magnetoimpedance effect of manganites, the magnetic field not only decreases the permeability μt, but also reduces the resistivity ρ by aligning the local spins and varying the transfer integral tij. The AC magnetoimpedance participated by the DC colossal magnetoresistance (CMR) in manganites, should be connected with the combined effects of double exchange interaction, electron–phonon coupling and skin effect. 相似文献
93.
M. A. Mojumder 《Journal of Superconductivity and Novel Magnetism》2009,22(4):417-425
We have calculated the planar magnetoresistance of the doped cuprate superconductor in the ‘normal’ state; the results are
in agreement with the divergence of the magnetoresistance near T
c
, and other unexplained data. Argument and evidence have been known for assuming that the ‘normal’ state in the doped cuprate
is mainly a two-channel Kondo lattice. In the common moderately disordered nonstoichiometrically doped cuprate, in contrast with the fully ordered crystal, the two-channel Kondo fixed point is effectively stable.
相似文献
94.
We report in this paper the synthesis, the sintering and the properties of La0.8Sr0.2MnO3 (LSMO) and BaZrO3 (BZ) compound using microwave heating. The starting raw material was prepared by solid state reaction. Synthesis and sintering were carried out using an indirect microwave heating process. SiC susceptor tube was utilized to produce the indirect heating in a microwave symmetrical single mode cavity TE10p. The LSMO and BZ phases have been successfully sintered in a microwave cavity in a very short time. Scanning electron microscopy (SEM), X-ray diffraction (XRD), magnetic or dielectric and electrical properties were carried out for both processing conditions, i.e., using classical and microwave heating. The results and advantages of this microwave process to synthesize many materials with various physicals properties are discussed. 相似文献
95.
96.
F. Mitsugi T. Ikegami K. Ebihara J. Narayan A. M. Grishin 《Science and Technology of Advanced Materials》2001,2(3-4):525-531
We prepared the colossal magnetoresistive La0.8Sr0.2MnO3 thin films on single crystal MgO, SrTiO3 and LaAlO3 substrates by KrF excimer pulsed laser deposition technique. The thickness dependence of the structural, electric and magnetic properties of the LSMO films on different substrates is reported. The integration of the ferroelectrics with the colossal magnetoresistance thin film was achieved. The plasma plume ablated from target was investigated by intensified charge coupled device and optical emission spectroscopy. 相似文献
97.
《Ceramics International》2022,48(1):407-414
Recently, La0.67Ca0.33MnO3 has garnered significant research attention due to its peculiar physical properties, such as colossal magnetoresistance and metal insulator transitions. The practical applications of these materials are mainly determined by the temperature coefficient of resistance (TCR) and magnetoresistance (MR). As a mature synthesis route, the sol-gel method can prepare high-quality ceramic targets. Herein, using methanol as a solvent, La0.67Ca0.33Mn1-xCoxO3 (0 ≤ x ≤ 0.06) polycrystalline ceramics are prepared using the sol-gel method and the influence of Co doping on electrical and magnetic properties is systematically studied. Co doping increases the grain size, and is helpful to improve TCR and MR. In addition, with increased Co doping, the double exchange is weakened, and the ferromagnetism is depressed, which leads to a decrease in TMI. The results reveal that the TCR and MR can be optimized by tuning the Co content. For instance, we have achieved a TCR value of 44.2% · K?1 at x = 0.02 and an MR value of 76.3% at x = 0.04, showing the promise of Co-doped La0.67Ca0.33MnO3 ceramics in a wide array of applications, such as bolometers and magnetic sensors. 相似文献
98.
《Ceramics International》2020,46(3):3339-3344
Bismuth telluride (Bi2Te3) is so far the best thermoelectric material for applications near room temperature, and also exhibits large magnetoresistance. While the electrochemical deposition approach can achieve effective growth of the Bi2Te3 films at micrometer thickness, the magnetoresistance transportation behavior of the electrochemically deposited Bi2Te3 films is yet not clear. In this work, we demonstrate the thermoelectric and magnetoresistance behaviors of the micrometer thick Bi2Te3 films deposited via electrochemical deposition approach. The optimum thermoelectric power factor is observed in the Bi2Te3 sample with electrochemical deposition thickness of ~6 μm followed by rapid photon annealing treatment, reaching the magnitude of ~1 μWcm−1K−2 that is similar to the previous reports. In contrast to the single crystalline or vacuum deposited Bi2Te3 or Bi2Se3 films, the electronic transportations of the electrochemically deposited Bi2Te3 are more influenced by the carrier scatterings by the grain boundaries and lattice defect. As a result, their magnetoresistance (MR) shows a distinguished non-monotonic behavior when varying the magnetic field, while the magnitude of their MR exhibits a positive temperature dependence. These MR behaviors largely differ to the previously reported ones from the single crystalline or vacuum deposited Bi2Te3 or Bi2Se3, in which cases their MR monotonically increases with the magnetic field and exhibits negative temperature dependence. This work reveals the previously overlooked role of grain boundary that also regulates the transportation properties of bismuth chalcogenides in the presence of magnetic field. 相似文献
99.
Magnetic and transport properties of a hard–soft spin valve structures have been investigated. A first series of sandwiches composed of an artificial antiferromagnetic (AAF) Co/Ru/Co sandwich decoupled from a soft Fe/Co buffer layer as follows: Fe50 Å/Co5 Å/Cu30 Å/Co30 Å/Ru5 Å/Co30 Å/Cu20 Å/Cr20 Å has been prepared. This sandwich presents a giant magnetoresistance (GMR) of 1.7% and an exchange coupling strength of approximately −1.73 erg/cm2. Afterwards, we have grown a second series of sandwiches in which the Cu/Cr capping layer has been replaced by a 15-Å thin semiconductor layer of ZnS, covered by a soft ferromagnetic layer of Co5 Å/Fe50 Å. Surprisingly, the giant magnetoresistance for the last sandwiches has been increased by a factor of 2, up to 4%. To explain this non-expected result, we have performed atomic force microscope imaging at the semiconductor layer surface. The results show that the semiconductor layer is not homogeneous and contains a non-negligible density of pin-holes, that are responsible of a direct magnetic coupling between the upper 30 Å Co layer of the AAF and the Co 5 Å/Fe 50 Å bilayer. This coupling induces a strong asymmetry between the magnetic layers of the AAF and consequently an enhancement of the GMR. 相似文献
100.
A. N. Lavrov L. P. Kozeeva M. R. Trunin V. N. Zverev 《Journal of Superconductivity and Novel Magnetism》2009,22(1):63-66
The remarkable sensitivity of the c-axis resistivity and magnetoresistance in cuprates to the spin ordering is used to clarify the doping-induced transformation
from an antiferromagnetic (AF) insulator to a superconducting (SC) metal in RBa2Cu3O6+x
(R = Lu, Y) single crystals. The established phase diagram demonstrates that the AF and SC regions apparently overlap: The superconductivity
in RBa2Cu3O6+x
, in contrast to La2−x
Sr
x
CuO4, sets in before the long-range AF order is completely destroyed by hole doping. Magnetoresistance measurements of superconducting
crystals with low T
c
≤15–20 K give a clear view of the magnetic-field induced superconductivity suppression and recovery of the long-range AF state.
What still remains to be understood is whether the AF order actually persists in the SC state or just revives when the superconductivity
is suppressed, and in the former case, whether the antiferromagnetism and superconductivity reside in nanoscopically separated
phases or coexist on an atomic scale. 相似文献