Resistive switching in ultra-thin La0.7Sr0.3MnO3/SrRuO3 superlattices

Abstract

Superlattices may play an important role in next generation electronic and spintronic devices if the key-challenge of the reading and writing data can be solved. This challenge emerges from the coupling of low dimensional individual layers with macroscopic world. Here we report the study of the resistive switching characteristics of a of hybrid structure made out of a superlattice with ultrathin layers of two ferromagnetic metallic oxides, La 0.7 Sr 0.3 MnO 3 (LSMO) and SrRuO 3 (SRO). Bipolar resistive switching memory effects are measured on these LSMO/SRO superlattices, and the observed switching is explainable by ohmic and space charge-limited conduction laws. It is evident from the endurance characteristics that the on/off memory window of the cell is greater than 14, which indicates that this cell can reliably distinguish the stored information between high and low resistance states. The findings may pave a way to the construction of devices based on nonvolatile resistive memory effects. Figure 1. Misfit dislocations were found at the interfaces between the La 0.7 Sr 0.3 MnO 3 and SrRuO 3 layers. However, the interfacial atomic layers were affected by intermixing; both A-site (La/Sr) and B-site (Mn/Ru) cations intermix in 1-2 unit cells across the interface, as marked by the rectangles in Fig 1(b). The contacts ( Fig. 1(a)) to the top layer were made by the wire bonder, the distance between two planar electrodes is 1 mm. KeywordsUsing Keithley 2400, two probe method was employed in order to measure I -V characteristics.All the measurements were carried out at room temperature. Top SRO layer showed the resistance ~ KΩ. At this point it is worth quoting about the nature of SRO layer with different superlattice structures where essentially SRO layer behaved vividly in its bulk and ultra-thinfilm form. On top of that in general an important issue on using ultrathin films of metal oxides is the significant enhancement in the resistivity, which has been clearly manifested in SRO thin films [19][20][21][22] .Before the forming process, resistive switching at low voltages is not consistently observed in LSMO/SRO superlattice, between -1 V and +1 V. In order to make filaments between the electrodes, I -V characteristics were measured by sweeping voltage from 0 to 20 V with a current compliance of 10 mA. Essentially, the electro-forming process is necessary to get a stable and reproducible resistive switching behavior in the resistive switching devices. Compliance current of 10 mA is used to avoid the dielectric break down of the device during the forming process due to leakage current which may arise by the application of very high voltages.Essentially, during this process, current -limited electric breakdown is induced in the Fig. 2(b) shows the same graph in logarithmic plot. As soon as we increased the compliance limit until 100 mA, we could see dielectric breakdown in the device. Hence, we fixed the compliance limit to 10 mA for all the devices.To probe the current conduction mechanism of LSMO/SRO superlattice...

Strain‐Mediated Inverse Photoresistivity in SrRuO3/La0.7Sr0.3MnO3 Superlattices

“…It is known that photoelectrons are excited in SRO sublayers while being illuminated . Basically these hot electrons should be spinless since SRO is paramagnetic at room temperature, and can easily cross the interfaces via the overlap of Ru 4d and Mn 3d orbitals due to the small band offsets between LSMO and SRO . Moreover, when LSMO suffers higher strain, the preferred orbital occupancy along its elongated direction would have lower energy level and become more stable due to the strain‐driven Jahn–Teller effect, which allows more electrons hopping into this orbital state (i.e., x 2 – y 2 for SL STO and 3 z 2 – r 2 for SL LAO ) .…”

Structural, transport and optical properties of (La0.6Pr0.4)0.65Ca0.35MnO3nanocrystals: a wide band-gap magnetic semiconductor

“…[1][2][3][4][5][6][7][8][9][10][11] Manganite materials have been used in different electronic devices such as magneto-tunable photocurrent devices, resistive switching devices, and spin hall magnetoresistive devices. [12][13][14][15][16][17][18] The parent compound LaMnO 3 is known to be an antiferromagnetic insulator, while divalent cation (Ca 2+ , Sr 2+ and Ba 2+ ) doping induces paramagnetism with polaron type conductivity at high temperatures, and metallic ferromagnetism below the Curie temperature T C . The origin of ferromagnetism has been attributed to the double-exchange interaction between the valence electronic states of Mn 3+ -O −2 -Mn 4+ .…”

Low-temperature anomalous spin correlations and Kondo effect in ferromagnetic SrRuO3/LaNiO3/La0.7Sr0.3MnO3Ghosh1, Tanguturi2, Pramanik3 et al. 2019Phys. Rev. B19060View full textAdd to dashboardCite

“…These perovskite materials (LSMO/SRO superlattices) have also been demonstrated as a promising candidate for an alternative roomtemperature magnetic refrigerators at very small scales, as they have better magnetocaloric effect and cooling power 60 . In addition owing to their bipolar resistive switching memory effect and inverted hysteresis with giant exchange bias these superlattices can be a major component for the storage device 61,62 . Apart from their superior optoelectronic features these materials exhibit better thermal response.…”