19 research outputs found
Influence of thermal boundary conditions on the current-driven resistive transition in VO 2
Conducting interfaces between band insulating oxides: the LaGaO3/SrTiO3
We show that the growth of the heterostructure LaGaO3/SrTiO3 yields the
formation of a highly conductive interface. Our samples were carefully analyzed
by high resolution electron microscopy, in order to assess their crystal
perfection and to evaluate the abruptness of the interface. Their carrier
density and sheet resistance are compared to the case of LaAlO3/SrTiO3 and a
superconducting transition is found. The results open the route to widening the
field of polar-non polar interfaces, pose some phenomenological constrains to
their underlying physics and highlight the chance of tailoring their properties
for future applications by adopting suitable polar materials.Comment: in press Appl. Phys. Lett. 97, 1 (2010
Strain, Young's modulus, and structural transition of EuTiO3 thin films probed by micro-mechanical methods
EuTiO3 (ETO) is a well-known complex oxide mainly investigated for its
magnetic properties and its incipient ferro-electricity. In this work, we
demonstrate the realization of suspended micro-mechanical structures, such as
cantilevers and micro-bridges, from 100 nm-thick single-crystal epitaxial ETO
films deposited on top of SrTiO3(100) substrates. By combining profile analysis
and resonance frequency measurements of these devices, we obtain the Young's
modulus, strain, and strain gradients of the ETO thin films. Moreover, we
investigate the ETO anti-ferro-distorsive transition by temperature-dependent
characterizations, which show a non-monotonic and hysteretic mechanical
response. Comparison between experimental and literature data allows us to
weight the contribution from thermal expansion and softening to the tuning
slope, while a full understanding of the origin of such a wide hysteresis is
still missing. We also discuss the influence of oxygen vacancies on the
reported mechanical properties by comparing stoichiometric and oxygen-deficient
samples.Comment: 8 pages, 5 figures; 7 Supplementary Material section
Persistent photoconductivity in 2-dimensional electron gases at different oxide interfaces
We report on the transport characterization in dark and under light
irradiation of three different interfaces: LaAlO3/SrTiO3, LaGaO3/SrTiO3, and
the novel NdGaO3/SrTiO3 heterostructure. All of them share a perovskite
structure, an insulating nature of the single building blocks, a polar/non-
polar character and a critical thickness of four unit cells for the onset of
conductivity. The interface structure and charge confinement in NdGaO3/SrTiO3
are probed by atomic-scale- resolved electron energy loss spectroscopy showing
that, similarly to LaAlO3/SrTiO3, extra electronic charge confined in a sheet
of about 1.5 nm in thickness is present at the NdGaO3/SrTiO3 interface.
Electric transport measurements performed in dark and under radiation show
remarkable similarities and provide evidence that the persistent perturbation
induced by light is an intrinsic peculiar property of the three investigated
oxide-based polar/non-polar interfaces. Our work sets a framework for
understanding the previous contrasting results found in literature about
photoconductivity in LaAlO3/SrTiO3 and highlights the connection between the
origin of persistent photoconductivity and the origin of conductivity itself.
An improved understanding of the photo- induced metastable electron-hole pairs
might allow to shed a direct light on the complex physics of this system and on
the recently proposed perspectives of oxide interfaces for solar energy
conversion.Comment: 11 pages, 7 figure
Mechanical Characterization of (La,Sr)MnO3 Microbridges for Thermometric Applications
MicroElectroMechanical Systems (MEMS) made of heterostructures of crystalline oxide materials with targeted physical properties may be applied as sensors having different integrated functionalities. In this work, we explore the feasibility of manganite thin film based epitaxial MEMS for thermometric micromechanical sensing. We investigate the mechanical properties of La1âxSrxMnO3, with x â 1/3, freestanding microbridges as a function of temperature for applications in the field of micromechanical temperature sensors