Voltage bias induced modification of the transport property of all oxide Pr0.5Ca0.5MnO3/SrTi0.95Nb0.05O3 junctions

Abstract

In this paper we report what happens to a virgin oxide junction Pr0.5Ca0.5MnO3/SrTi0.95Nb0.05O3 (PCMO/Nb:STO), when it is subjected to cycling of voltage bias of moderate value (±4 V). It is found that the initial cycling leads to formation of a permanent state of lower resistance where the lower resistance arises predominantly due to the development of a shunt across the device film (PCMO). On successive voltage cycling with increasing magnitude, this state transforms into states of successive lower resistance that can be transformed back to the initial stable state on cycling to below a certain bias. A simple model based on p-n junction with shunt has been used to obtain information on the change of the junction on voltage cycling. It has been shown that the observation can be explained if the voltage cycling leads to lowering of the barrier at the interface and also reduction in series resistance. It is suggested that this lowering can be related to the migration of oxygen ions, which causes the vacancies at the junction region. Cross-sectional imaging of the junction shows formation of permanent filamentary bridges across the thickness of the PCMO after the virgin p-n junction is first taken through a voltage cycle, which would explain the appearance of a finite shunt across the p-n junction.

Bipolar resistive switching in YMnO3/Nb:SrTiO3pn-heterojunctions

“…It is expected that mobile defects together with other trapping sites form paths which become conductive after being filled with injected electrons, as indicated by transition from trapped-controlled to trap-filled SCL currents in higher electric fields. Formation of filaments consisting of filled trapping sites which shunt bottom and TEs was proposed as a mechanism of the set process during BRS in LaAlO 3 /SrTi 0.93 Nb 0.07 O 3 [31], and in Pr 0.5 Ca 0.5 MnO 3 /SrTi 0.95 Nb 0.05 O 3 [32]. These filaments are significantly different from filaments observed e.g.…”

Ferromagnetism in Lightly Doped Pr1–xCaxMnO3 (x = 0.023, 0.036) Nanoparticles Synthesized by Microwave Irradiation

“…The complexity of these systems due to the characteristic lattice distortions in the whole range of doping concentrations is directly responsible for their tunability, and the balance between different competing phases can produce significant changes in the physical properties. Mostly studied as single crystals and thin films, the hole-doped Pr 1– x Ca x MnO 3 (PCMO) phases experience lattice distortion involving the Jahn–Teller effect of Mn 3+ ions leading to distortions and puckering of the Mn 3+ O 6 octahedra. The formula Pr 3+ 1– x Ca 2+ x [Mn 3+ 1– x Mn 4+ x ]O 2– 3 is obtained when the concentration of Mn 3+ is formally decreased by Ca 2+ substitution.…”

Room temperature resistive state switching with hysteresis in GdMnO3 thin film with low threshold voltage

“…Modifications of oxygen vacancy by the applied field has been proposed as the cause of such switching. 6,7 In undoped materials like SrTiO 3 (that has a fixed valency for the transition metal ion), the observed resistive switching needs much larger threshold field and the switching with memory (or hysteresis) was related to manipulation of oxygen vacancies by the applied field. 8 Thus, the switching phenomena (with hysteresis) reported earlier has predominantly an ionic origin.…”