Two-dimensional Ti 3 C 2 T x MXene-based hybrids-anchored magnetic metal nanoparticles show a huge potential application as effective wave absorbers due to the synergistic electromagnetic (EM) loss effect. In this work, uniform and size-controllable nickel, cobalt, or nickel−cobalt alloy nanoparticles were in situ grown on the surface of MXene via a facile and moderate co-solvothermal method for the first time. As an example, a nickel nanoparticles-anchored MXene (Ni@MXene) hybrid was homodispersed into dielectric polyvinylidene fluoride to develop its EM waveabsorbing capacity to a great extent. As expected, the results showed strong reflection loss (RL min = −52.6 dB at 8.4 GHz), broad effective absorption bandwidth (EAB = 3.7 GHz including 71% of X-band), low loading (10 wt % Ni@MXene), and thin thickness (3.0 mm). By adjusting the sample thickness, EAB can cover completely the whole X-band with a maximum of 6.1 GHz, showing a huge potential of Ni@MXene hybrid applying as aircraft stealth coating. The mechanism analyses revealed that the excellent impedance matching, magnetocoupling effect, conductance, magnetic loss, and multiple scatterings contribute to the splendid EM wave-absorbing performance of the Ni@MXene hybrid. Considering the excellent overall performance, the Ni@MXene hybrid was identified as a promising candidate for EM wave absorption.
Complex oxide heterointerfaces provide a platform to manipulate spin−orbit coupling under the broken inversion symmetry. Moreover, their weak antilocalization (WAL) effect displays quantum coherent behavior due to the strong spin−orbit coupling. Herein, we break through the limitation of lattice mismatch at ReAlO 3 /STO (Re = La, Pr, Nd, Sm, and Gd) heterointerfaces and obtain their twodimensional electric gas (2DEG) by spin coating. The effect of different Re elements in the resulting quantum corrections on the conductivity is investigated. It is observed that the conductivity of heterointerfaces is reduced with larger atomic numbers due to the ionization potential of Re elements. Moreover, magnetoresistance (MR) measurements in a perpendicular or a parallel field distinctly uncover strong Rashba spin−orbit coupling (SOC) in ReAO/STO samples besides SAO/STO (Re = Sm) and GAO/STO (Re = Gd), and the effective fields of the SOC (H so ) gradually increase from LAO/STO (Re = La, H so = 0.82 T) to NAO/ STO (Re = Nd, H so = 1.37 T) at 2 K. The competition between SOC scattering and inelastic scattering is revealed through a temperature-dependence study of MR, and the WAL−weak localization transition is at about 6 K. Furthermore, unambiguous results of the Kondo effect, nonlinear Hall, hysteresis loop, and Rashba SOC suggest the coexistence of WAL at the PAO/STO (Re = Pr) heterointerface with exchange coupling between the localized magnetic moment and the itinerant electron. These results pave a unique route for the exploration of spin-polarized 2DEGs at oxide heterointerfaces.
Although the amorphous two-dimensional electron gas (a-2DEG) of oxides provides new opportunities to explore nanoelectronic as well as quantum devices, the intrinsic effect of rare earth (Re = La, Pr, Nd, Sm, Gd, and Tm) elements at ReAlO 3 /SrTiO 3 heterointerfaces is still largely unknown and needs to be addressed systematically. Herein, we first propose that the ionization potential of Re elements is a critical factor for the 2DEG fabricated by chemical spin coating. Furthermore, the photoresponsive properties of heterointerfaces are investigated comprehensively with the ionization potential ranging from 35.79 to 41.69 eV. The results show that the sheet resistances significantly increase with increasing the ionization potential, and a resistance upturn phenomenon is observed at TmAlO 3 /SrTiO 3 heterointerfaces, which can be attributed to the weak localization effect theoretically. The most important observation is the dramatic transition from negative (−178.3%, Re = La) to positive (+89.9%, Re = Gd) photoresponse at ReAlO 3 /SrTiO 3 heterointerfaces under the irradiation of 405 nm light at 50 K. More remarkably, a unique recovery behavior of transient−persistent photoconductivity coexistence at low temperatures is discovered at the TmAlO 3 /SrTiO 3 heterointerface. This work reveals an effective approach to tune the transport and photoresponsive properties by changing Re elements and paves the way for the application of all-oxide devices.
Chemical doping is a dominating method in manipulating oxide two-dimensional gas (2DEG). However, enhancing doping level while keeping metallic conducting remains as a challenge, which limits detailed knowledge in 2DEG...
Manipulating the photoresponse of two-dimensional electron gas at the interface of complex oxides is attracting tremendous interest because of its potential applications in photoelectric devices. In this study, transport behaviors of LaAlO3/SrTiO3 heterointerfaces tuned by a nickelate buffer layer under light irradiation have been investigated. With the increasing thickness of the buffer layer, the LaAlO3/SrTiO3 interfaces exhibit the metal-to-insulator transition. More importantly, we also observe a substantial enhancement in the photoresponse under a 360 nm light irradiation and the relative change in the resistance of heterointerfaces is enhanced from 6.8% (without a buffer layer) to 50 139% (with a 1.6 u.c. buffer layer) at 300 K. Moreover, the heterointerfaces exhibit a state of change from persistent to transient photoconductivity. These emerging results are analyzed in view of the relevant mechanisms of band bending and lattice effects. This work provides experimental support for the application of perovskite oxides in interface optoelectronics.
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