# Switching dynamics of oxygen-vacancy memristors based on cuprate superconductors

V. Rouco, A. Lagarrigue, V. Humbert, C. De Dios, S. Carreira, C. Leon, J.

Santamaría, Javier Villegas

► To cite this version:

V. Rouco, A. Lagarrigue, V. Humbert, C. De Dios, S. Carreira, et al. Switching dynamics of oxygen-vacancy memristors based on cuprate superconductors. Applied Physics Letters, 2025, 127 (24), pp.241602. 10.1063/5.0304575. hal-05456850

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Switching dynamics of oxygen-vacancy memristors based on cuprate superconductors

V. Rouco<fnref n="1" />, A. Lagarrigue<fnref n="2" />, V. Humbert<fnref n="2" />, C. de Dios<fnref n="2" />, S. Carreira<fnref n="2" />, C. Leon<fnref n="1" />, J. Santamaría<fnref n="1" /> and J.E. Villegas<fnref n="2" />

Resistive switching phenomena have attracted increased attention over the years because of their technological relevance, particularly for applications like non-volatile memories and memristors, of much interest for novel neuromorphic computation schemes. Devices based on complex oxides as are especially appealing, since these materials present a plethora of functionalities (magnetism, superconductivity, photoconductivity...) and resistive switching mechanisms. Determining their characteristic timescales is crucial, both for fundamental understanding and regarding the potential applications. Here, we analyze the resistive switching dynamics of tunnel junctions between a cuprate superconductor and a metallic counter-electrode, in which memristive behavior stems from an electrochemical redox reaction across their interface. We compare these junctions with similar ones in which a thin oxide ferroelectric layer is placed in between both electrodes, expected to promote faster ferroelectric switching effects. We find that all the junctions show similar dynamics, pointing to oxygen ion exchange as the dominant mechanism in all cases. Interestingly, very strong resistance switching effects are observed down to the 100 ns timescale, thus allowing for applications where fast switching is required, even at cryogenic temperatures at which superconducting effects can be exploited.

<footnote n="1">¹ Grupo de Física de Materiales Complejos, Dpto. Física de Materiales, Universidad Complutense de Madrid, 28040 Madrid, Spain.</footnote>

<footnote n="2">² Laboratoire Albert Fert, CNRS, Thales, Université Paris-Saclay, 91767 Palaiseau, France</footnote>
Neuromorphic computing is a promising approach to circumvent the so-called von Neumann bottleneck of conventional computing architectures [1]. Inspired by the operation principle of a biological brain, where information storage and processing are co-located, neuromorphic hardware is based on devices that emulate the functions of biological neurons and synapses [2]. It promises low power consumption and fast operation rates. Memristors are one of the most relevant devices for this type of bioinspired circuit [3–5]. They show a continuum of non-volatile resistance states, set by the history of applied electrical stimuli, and thus emulate the synapses [6] that connect neurons in artificial neural networks [6–8]. The individual operation speed is naturally a key parameter for the global performance of the network. This is even more crucial considering that it is nowadays not possible to reproduce the very high connectivity (10⁴/neuron) of the biological brain, and thus fast individual responses are required to minimize the number of connections [1] while trying to approach the typical brain processing timescale, for example ~10-100 ms for visual stimuli [9,10].

Oxide-based resistance switching devices are one of the most widely studied types of memristors which in some scenarios the resistance switching is governed by the motion of oxygen vacancies. The large variety of possible architectures spans from planar devices [11,12], to vertical architectures [13–15], including tunnel junctions. The latter device consists of two electrodes separated by a few-nanometers-thick insulating layer acting as an electron tunnel barrier, with often at least one of the electrodes being a strongly correlated oxide. These junctions are interesting for their multifunctional character: a variety of stimuli and mechanisms can drive the resistance switching. For example, in the case of ferromagnetic electrodes, the resistance change is caused by the switching of their relative magnetization direction via a magnetic field, yielding the so-called tunnel magnetoresistance (TMR) effect [16–18]. In junctions where the tunnel barrier is a ferroelectric, the electric-field-induced switching of the ferroelectric polarization also results in large resistance switching, which is called tunnel electroresistance (TER) [19]. The switching can be very fast (in the ~ns range [20]) and be combined with TMR in judiciously designed devices [16–19]. A different mechanism leading to electric-field-induced switching of the tunnel resistance is electrochemistry, which drives ion motion and exchange between the electrodes. This mechanism has sometimes been found to coexist, contaminate (and even overrule) ferroelectric effects in ferroelectric tunnel junctions [21–25].

Interestingly, recent works [24,26,27] have shown that electrochemistry alone, and particularly a reversible redox reaction between the electrodes, can be exploited to obtain a giant resistance-switching effect that is qualitatively and quantitatively similar to the TER. This can be realized in very simple junctions without a ferroelectric layer: just a single interface between a complex oxide and a metal with lower reduction potential. In these devices, a tunneling barrier is naturally formed due to local reduction/oxidation at each side of the interface. The extension of the reduced/oxidized layers can be varied *in operando* by driving oxygen ions/vacancies back and forth upon application of voltage pulses of varying amplitude and polarity, thus setting different remnant resistance states. In addition to producing giant electroresistance, the controlled oxygen vacancy concentration modulates the electrode's ground state: for instance, it shifts the critical temperature of high-temperature superconducting electrodes [24,28] or the metal-to-insulator transition temperature of Mott insulating ones [26]. The interest of these
functionalities is further enhanced by the fact that the redox reaction can be sensitive to optical stimuli, and thus the resistance and ground-state switching can be driven also by light pulses, enabling photomemristive behavior [27].

The switching behavior of the above oxygen-vacancy memristors has been explored only for long response timescales, in the range of seconds. Here we probe it over much shorter time scales, down to the hundreds of ns. We find that, while the electroresistance (defined as $ER \equiv G^{ON}/G^{OFF}$, ratio between the highest (ON) and lowest (OFF) conductance state) gradually decreases as the switching rate is increased, a very large $ER > 1000\%$ is still observed for switching times as short as 100 ns –the shortest we can probe. Comparison of devices with and without a ferroelectric layer in between the electrodes show qualitatively similar behavior. Quantitatively, however, we find that the addition of the ferroelectric layer significantly lowers $ER$ and leads to faster degradation of the device performances upon shortening the switching times, indicating that ferroelectric effects do not synergize with electrochemical ones, but rather hinder them. These results demonstrate that pure redox tunneling memristors are promising for applications that require fast switching. This characteristic, together with their ultimate structural simplicity and sensitivity to diverse stimuli (electric and optical pulses), makes them promising for an enlarged field of applications.

A sketch of the junctions studied here is shown in Fig. 1a. These are based on a 30 nm $YBa_2Cu_3O_{7-x}$ (YBCO) bottom electrode. For some of the devices, a 3 nm $BiFeO_3$ (BFO) doped with Mn (5%) as a ferroelectric barrier is deposited on YBCO. Both YBCO and BFO (when present) are grown by *in situ* pulsed laser deposition on a $SrTiO_3$ (100) substrate. After growth, the sample surface is covered with resist via spin-coating to perform standard photolithography to define micrometric apertures through which a top electrode (100 nm of the amorphous alloy $Mo_{80}Si_{20}$, hereafter referred to as MoSi) is deposited by sputtering. This way, MoSi contacts the oxide structure yielding junctions for electrical measurements in current-perpendicular-to-plane configuration. The junctions' area is in the range of 10 to 200 µm². We selected MoSi as the top electrode because we have used this material in earlier studies on oxygen-vacancy memristors [24], which provides us with a well-controlled system to investigate the switching dynamics. However, we stress that similar memristive effects are expected if MoSi is replaced by other high-reduction-potential materials such as Al [28] or Indium Tin Oxide [27]. In contrast, noble metals such as Au will result in much weaker conductance switching effects [24]. The above fabrication steps are described in more detail elsewhere [24] where we also demonstrate the uniformity of the junctions across different BFO thicknesses and confirm the absence of pinholes.

Electrical characterization was performed with a two-terminal configuration as shown in Fig. 1a. The bottom YBCO is grounded, and the top MoSi is connected to an SMU Keithley 2600B series in parallel with an arbitrary function generator (Tektronix AFG 3021B). 50 Ω commercial BNC cables were used to ensure the impedance matching between the device and the measurement instruments. The SMU is used to apply slow voltage sweeps (from 0.1 V/s to 16.2 V/s), and the AFG is used to apply voltage pulses whose duration can be set in the 100 ms to 100 ns range. To ensure that the voltage applied by the AFG effectively drops between the junction electrodes, the SMU is configured in high-impedance output-off mode during the application of pulses. We have also
performed tests to verify that the shape and amplitude of the voltage pulses reaching the junction are identical to those generated by the AFG (see Fig. S1 of the Supplementary Material). The measurements were carried out in a closed cycle He cryostat that allows varying the temperature between 10 K and 300 K.

The switching behavior is studied by setting junction conductance states via “write” voltages $V_{write}$. This is done in two ways. In slow switching measurements, we ramp the applied voltage from 0 V to $V_{write}$ at a constant rate of 0.1 V/s using the SMU. This method is called Ramped-$V_{write}$ hereafter. In fast measurements, we apply a voltage pulse of $V_{write}$ amplitude and a given duration (down to 100 ns) using the AFG. This method is hereafter referred as Pulsed-$V_{write}$. Regardless of the write method, once $V_{write}$ is applied the remnant conductance state $G$ is “read” by measuring $I(V)$ during a voltage sweep between 200 mV and -200 mV and numerically calculating the differential conductance $f$ for at 100mV bias. As it will become evident below, the reading bias voltage is low enough to avoid modifying the “written” conductance state. A sketch of the applied voltages vs. time during a sequence of measurements is shown in Fig. 1b both for the Ramped-$V_{write}$ and Pulsed-$V_{write}$ methods.

Fig. 1c shows the typical conductance $G$ vs. $V_{write}$ as obtained through the Ramped-$V_{write}$ method for junctions with 0 nm and 3 nm thick BFO layer. $I(V)$ curves during this $V_{write}$ protocol when maximum $V_{write}$'s are applied are shown in Fig. S2 of the Supplementary Material. Measurements show a qualitatively similar behavior for both types of junctions, with a hysteretic switching between a high (ON) and low (OFF) conductance states upon application of a sufficiently high negative/positive $V_{write}$. Notice that remnant intermediate conductance states are achieved between the two extrema, and that the loops are asymmetric, as expected because the switching from high to low conductance is spontaneous from the electrochemical point of view [24,28]. The switching voltages, of the order of a few volts, are similar for both types of junctions, that is, regardless of the presence of the BFO interlayer. However the $ER$ is up to one order of magnitude larger in the absence of the ferroelectric layer, in agreement with earlier experiments [24]. The $ER$ dependence on temperature is shown in Fig. 1d. This shows that $ER$ is gradually enhanced with decreasing temperature, and that this trend is stronger in the junctions without ferroelectric barrier. The above behaviors, and particularly the hysteretic loops in Fig. 1c and the extracted $ER$, were found to be independent of the $V_{write}$ sweep rate in the explored range 0.1 V/s - 16.2 V/s.

Fig. 2 shows the conductance $G$ vs. $V_{write}$ at 10 K measured via the Pulsed-$V_{write}$ method for junctions with 0 nm BFO (Fig. 2a) and 3 nm BFO (Fig. 2b), using different pulse durations between 100 ns and 100 ms (see legend in each panel). The sequence of Pulsed-$V_{write}$ was applied to complete 2 OFF → ON cycles that appear superposed in each panel. Both types of junctions show a gradual increase of the $ER$ as the pulse duration is increased, until it essentially saturates above ~1 ms pulses. Notice that the OFF state conductance level is nearly the same for all pulse durations, while the ON conductance level achieved upon switching clearly becomes lower as pulses are shortened below 1 ms. Direct conductance measurements (I/V) at 100 mV are compared in Fig. S3 of the Supplementary Material with the differential conductance (dI/dV) data shown in Fig. 2a. Apart from minor quantitative differences in the absolute resistance values, the overall dependence of the electroresistance on pulse duration remains fully consistent with the
original results. As shown in Fig. S1 of the Supplementary Material, the effective $V_{write}$ pulse waveform remains square for all pulse durations, except for the shortest one (100 ns). This confirms that the variations observed in Fig. 2 cannot be attributed to distortions in the pulse shape as the duration decreases, but rather to the intrinsic switching dynamics of the junctions.

Similarly, as in measurements with the Ramped-$V_{write}$ method, here larger ER values are systematically obtained in junctions without ferroelectric interlayer. This is illustrated in Fig. 3a and Fig. 3b, which shows ER vs. pulse duration measurements at 10 K and 200 K for both types of junctions. In fact, at 200 K, a significant ER is only observed for junctions without ferroelectric interlayer (the green area indicates ER>1). On the other hand, the same figures illustrate that the gradual weakening of ER as pulses are shortened is more pronounced in junctions with the ferroelectric interlayer.

To better compare the evolution of junctions with and without ferroelectric interlayer, for each junction, we normalized the ER data to its largest value, which is always observed at the lowest temperature (T=10 K) and longer pulse duration (100 ms). Thus Figs. 3c and 3d display a contour map of the normalized electroresistance $er_t(T) = ER_t(T)/ER_{100\ ms}(10\ K)$ as a function of the pulse duration t and T. The bluish color corresponds to the region where the junctions show low $er$. One can see that in the sample with ferroelectric interlayer this region occupies a larger portion of the map, and particularly that it covers lower temperatures than for the sample without the ferroelectric interlayer. Conversely the greenish and reddish region, which corresponds to the intermediate and largest $er$ respectively, is restricted to longer pulse durations and low temperatures in the case of *in the junction with ferroelectric interlayer*.

Fig. 4 shows the temporal evolution of the ON/OFF states after they are set through the Ramped-$V_{write}$ method at 100 K, giving hints on the relaxation dynamics of each state for both junctions. After application of $V_{write}$, we measure the current across the junction under constant bias (100 mV) as a function of time t, for up to 2 hours. In the figure, the measured current is normalized by its value at t = 0 for better comparison between the two types of junctions. In both cases, the OFF state current shows no significant evolution over time. Contrarily, in the ON state, the current decays steadily for both types of junctions. Yet the retention is relatively high, since at the end of the experiment the current is still around 85% of that at t=0. These results show that the OFF state is stable and that the ON state slowly evolves towards a lower conductance state, for both types of junctions.

The relaxation behavior of Fig. 4 is as expected from the redox mechanism leading to the resistance switching [24,26–28]: the lower reduction potential of the top electrode (dominated by that of Mo) as compared to that of YBCO (dominated by Cu) leads to oxidation of the former, at the expense of creating near the interface a severely oxygen-depleted (insulating) YBCO layer that behaves as a tunnel barrier for electrons. This natural reaction leads to the OFF state, which is stable. The redox reaction is reversed upon application of negative $V_{write}$, leading to a thinning of the oxygen-depleted layer, and eventually to the ON state. This state is out of equilibrium from the electrochemical point of view, and therefore tends to relax towards the OFF state over time.
The similar behavior for both types of junctions indicates that ferroelectricity is not playing a major role in the junction with BFO interlayer. This is further supported by the fact that the *ER* starts diminishing for pulse durations in the ms range (Fig. 2), which is much longer than the switching time of ferroelectrics (~ns range [20] or less). Further, comparison between Fig. 3a and 3b shows that *ER* decreases with decreasing pulse duration more strongly in samples with BFO interlayer (by a factor ~5 as the pulse duration is reduced from 10⁻¹ s to 10⁻⁷ s) than without it (by a factor ~2 in the same range). This indicates a slower OFF to ON dynamics for the junction with ferroelectric interlayer (Fig. 3). Moreover, from the relaxation behavior shown in Fig. 4, the characteristic relaxation time was extracted by fitting the normalized current as a function of time with a stretched exponential function, e⁻(t/τ)β, where τ is the characteristic relaxation time and β is a fitting parameter. The resulting fits yields longer relaxation rates in the presence of the 3 nm BFO layer, τ ~ 10¹¹ s, that for the junction without BFO for which τ ~ 10⁸ s. This is not surprising in the redox scenario, since the forced oxygen ion migration from MoSi into YBCO is expectedly more difficult when the BFO layer is present. That also explains the overall weaker *ER* observed in the presence of the ferroelectric layer.

In summary, we have studied the switching dynamics of oxygen vacancy memristors consisting of an interface between a cuprate superconductor and a low reduction potential material. We have demonstrated that these simple devices are fast enough to operate with switching rates in the 100 ns range while providing a large electroresistance ratio exceeding 1000%. Incorporation of a thin ferroelectric layer into the junction does not lead to a synergy of ferroelectric and ion-migration effects and slightly degrades performance rather than enhancing it. These results prove that devices of ultimate simplicity, —a single metal/oxide interface— can be used as fast memristors operating down to cryogenic temperatures. Nevertheless, given the redox nature of the mechanism and the materials involved, careful optimization is required to balance two competing factors: maximizing the resistive switching ratio while minimizing the spontaneous relaxation of the resistance states.

Work supported by EIC Pathfinder Open 101130224 "JOSEPHINE". V.R. was supported by the Madrid Government (Comunidad de Madrid-Spain) under the Multiannual Agreement with Universidad Complutense de Madrid in the line Research Incentive for Young PhDs, in the context of the V PRICIT (Regional Programme of Research and Technological Innovation), and grant CNS2024-154507 funded by MCIN/AEI/ 10.13039/501100011033.

## AUTHOR DECLARATIONS

### Conflict of Interest

The authors have no conflicts to disclose.

### Author Contributions

**V. Rouco:** Investigation (equal), Formal analysis (equal), Writing - original draft (equal), Writing -review & editing (equal); **A. Lagarrigue** + **V. Humbert** + **C. de Dios** + **S. Carreira**: Investigation (equal), Writing -review & editing (equal); **C. León**: Writing -review & editing (equal), Resources (equal); **J. Santamaría**: Formal analysis (equal), Writing -review & editing (equal).
(equal), Resources (equal); **J.E. Villegas**: Conceptualization (lead), Formal analysis (equal), Writing - original draft (equal), Writing -review & editing (equal), Resources (equal)
## REFERENCES

[1] D. Marković, A. Mizrahi, D. Querlioz, and J. Grollier, *Physics for Neuromorphic Computing*, Nat. Rev. Phys. **2**, 499 (2020).

[2] J. Del Valle, J. G. Ramírez, M. J. Rozenberg, and I. K. Schuller, *Challenges in Materials and Devices for Resistive-Switching-Based Neuromorphic Computing*, J. Appl. Phys. **124**, 211101 (2018).

[3] W. Chen, L. Song, S. Wang, Z. Zhang, G. Wang, G. Hu, and S. Gao, *Essential Characteristics of Memristors for Neuromorphic Computing*, Adv. Electron. Mater. **9**, 2200833 (2023).

[4] Y. Zhang, Z. Wang, J. Zhu, Y. Yang, M. Rao, W. Song, Y. Zhuo, X. Zhang, M. Cui, L. Shen, R. Huang, and J. Joshua Yang, *Brain-Inspired Computing with Memristors: Challenges in Devices, Circuits, and Systems*, Appl. Phys. Rev. **7**, 011308 (2020).

[5] J. J. Yang, D. B. Strukov, and D. R. Stewart, *Memristive Devices for Computing*, Nat. Nanotechnol. **8**, 13 (2013).

[6] S. Saïghi, C. G. Mayr, T. Serrano-Gotarredona, H. Schmidt, G. Lecerf, J. Tomas, J. Grollier, S. Boyn, A. F. Vincent, D. Querlioz, S. La Barbera, F. Alibart, D. Vuillaume, O. Bichler, C. Gamrat, and B. Linares-Barranco, *Plasticity in Memristive Devices for Spiking Neural Networks*, Front. Neurosci. **9**, 51 (2015).

[7] D. B. Strukov and R. S. Williams, *Four-Dimensional Address Topology for Circuits with Stacked Multilayer Crossbar Arrays*, Proc. Natl. Acad. Sci. U. S. A. **106**, 20155 (2009).

[8] D. Ielmini and H. S. P. Wong, *In-Memory Computing with Resistive Switching Devices*, Nat. Electron. **1**, 333 (2018).

[9] S. Thorpe, D. Fize, and C. Marlot, *Speed of Processing in the Human Visual System*, Nature **381**, 520 (1996).

[10] M. C. Potter, B. Wyble, C. E. Hagmann, and E. S. McCourt, *Detecting Meaning in RSVP at 13 Ms per Picture*, Attention, Perception, Psychophys. **76**, 270 (2014).

[11] C. Acha and M. J. Rozenberg, *Non-Volatile Resistive Switching in the Dielectric Superconductor YBa$_2$Cu$_3$O$_7-\delta$, J. Phys. Condens. Matter** **21**, 045702 (2009).

[12] S. Marinković, D. Stoffels, S. Collienne, A. Fernández-Rodríguez, N. Mestres, A. Palau, and A. V. Silhanek, *Electromigration-Driven Weak Resistance Switching in High-Temperature Superconducting Devices*, Phys. Rev. B **110**, 165157 (2024).

[13] A. Sawa, *Resistive Switching in Transition Metal Oxides*, Mater. Today **11**, 28 (2008).

[14] B. K. Shibuya, R. Dittmann, S. Mi, and R. Waser, *Impact of Defect Distribution on Resistive Switching Characteristics of Sr$_2$TiO$_4$ Thin Films*, Adv. Mater. **22**, 411 (2010).

[15] T. Günkel, J. Alcalà, A. Fernández, A. Barrera, L. Balcells, N. Mestres, E. Miranda, J. Suñé, and A. Palau, *Field-Induced Phase Transitions in Cuprate Superconductors for Cryogenic in-Memory Computing*, Small **21**, 2411908 (2025).

[16] J. S. Moodera, L. R. Kinder, T. M. Wong, and R. Meservey, *Large Magnetoresistance at Room Temperature in Ferromagnetic Thin Film Tunnel Junctions*, Phys. Rev. Lett. **74**, 3273 (1995).

[17] J. M. De Teresa, A. Barthélémy, A. Fert, J. P. Contour, F. Montaigne, and P. Seneor, *Role of Metal-Oxide Interface in Determining the Spin Polarization of Magnetic Tunnel Junctions*, Science (80-). **286**, 507 (1999).
[18] E. Y. Tsymbal, A. Sokolov, I. F. Sabirianov, and B. Doudin, *Resonant Inversion of Tunneling Magnetoresistance*, Phys. Rev. Lett. **90**, 186602 (2003).

[19] D. J. Kim, H. Lu, S. Ryu, C. W. Bark, C. B. Eom, E. Y. Tsymbal, and A. Gruverman, *Ferroelectric Tunnel Memristor*, Nano Lett. **12**, 5697 (2012).

[20] J. Li, B. Nagaraj, H. Liang, W. Cao, C. H. Lee, and R. Ramesh, *Ultrafast Polarization Switching in Thin-Film Ferroelectrics*, Appl. Phys. Lett. **84**, 1174 (2004).

[21] M. Qian, I. Fina, M. C. Sulzbach, F. Sánchez, and J. Fontcuberta, *Synergetic Electronic and Ionic Contributions to Electroresistance in Ferroelectric Capacitors*, Adv. Electron. Mater. **5**, 1800646 (2019).

[22] V. Rouco, F. Gallego, D. Hernandez-Martin, D. Sanchez-Manzano, J. Tornos, J. I. Beltran, M. Cabero, F. Cuellar, D. Arias, G. Sanchez-Santolino, F. J. Mompean, M. Garcia-Hernandez, A. Rivera-Calzada, M. Varela, M. C. Muñoz, C. Leon, Z. Sefrioui, and J. Santamaría, *Ferroionic Inversion of Spin Polarization in a Spin-Memristor*, APL Mater. **9**, 031110 (2021).

[23] H. Kohlstedt, A. Petraru, K. Szot, A. Rüdiger, P. Meuffels, H. Haselier, R. Waser, and V. Nagarajan, *Method to Distinguish Ferroelectric from Nonferroelectric Origin in Case of Resistive Switching in Ferroelectric Capacitors*, Appl. Phys. Lett. **92**, 2006 (2008).

[24] V. Rouco, R. El Hage, A. Sander, J. Grandal, K. Seurre, X. Palermo, J. Briatico, S. Collin, J. Trastoy, K. Bouzehouane, A. I. Buzdin, G. Singh, N. Bergeal, C. Feuillet-Palma, J. Lesueur, C. Leon, M. Varela, J. Santamaría, and J. E. Villegas, *Quasiparticle Tunnel Electroresistance in Superconducting Junctions*, Nat. Commun. **11**, 658 (2020).

[25] Q. H. Qin, L. Äkäslompolo, N. Tuomisto, L. Yao, and S. Majumdar, *Resistive Switching in All-Oxide Ferroelectric Tunnel Junctions with Ionic Interfaces*, Adv. Mater. **28**, 6852 (2016).

[26] V. Humbert, R. El Hage, G. Krieger, G. Sanchez-santolino, A. Sander, S. Collin, J. Trastoy, J. Briatico, J. Santamaría, D. Preziosi, and J. E. Villegas, *An Oxygen Vacancy Memristor Ruled by Electron Correlations*, Adv. Sci. **9**, 2201753 (2022).

[27] R. El Hage, V. Humbert, V. Rouco, G. Sánchez-Santolino, A. Lagarrigue, K. Seurre, S. J. Carreira, A. Sander, J. Charliac, S. Mesoraca, J. Trastoy, J. Briatico, J. Santamaría, and J. E. Villegas, *Bimodal Ionic Photomemristor Based on a High-Temperature Oxide Superconductor/Semiconductor Junction*, Nat. Commun. **14**, 3010 (2023).

[28] A. Lagarrigue, C. de Dios, S. J. Carreira, V. Humbert, S. Mesoraca, J. Briatico, J. Trastoy, and J. E. Villegas, *Memristive Effects in YBa2Cu3O7-x Devices with Transistor-like Structure*, Supercond. Sci. Technol. **37**, 045007 (2024).
FIGURES

<figure><img src="image_2.png" /><figcaption>**Figure 1:** (a) Sketch of the device and the electrical connections. (b) Schematic representation of the measurement procedures used, where $V_{applied}$ corresponds to $V_{write}$ or $V_{read}$, as a function of time (c) Differential conductance $G = dI/dV$ measured at 100 mV as a function of ramped-$V_{write}$ for samples with 0 nm and 3 nm BFO barrier at 10 K. Two different loops for each case are shown to assess reproducibility. (d) Electroresistance $ER = G^{ON} / G^{OFF}$ as a function of temperature for samples with and without BFO.</figcaption></figure>
<figure><img src="image_3.png" /><figcaption>**Figure 2:** (a) Differential conductance at 10 K after applying Pulsed-V<sub>write</sub> with different pulse duration for the junction without ferroelectric interlayer. Grey arrows indicate the sense of the sweep. (b) Same experiment than in (a) but for the sample with 3 nm ferroelectric interlayer.</figcaption></figure>
<figure><img src="image_4.png" /></figure>

<figure><img src="image_5.png" /></figure>

<figure><img src="image_6.png" /></figure>

<figure><img src="image_7.png" /><figcaption>**Figure 3:** Electroresistance *ER* as a function of pulse duration at two different temperatures for samples with 0 nm (**a**) and 3 nm (**b**) BFO. Green colored area corresponds to the region where *ER* >1 for 200 K. (**c**) and (**d**) show the ratio between *ER* at different temperatures and pulse duration, and *ER* measured at 10K with pulses of 100 ms (*er*<sub>t</sub>) for samples without and with ferroelectric interlayer, respectively.</figcaption></figure>
<figure><img src="image_8.png" /><figcaption>**Figure 4:** Relaxation of the OFF and ON states for samples with (a) 0 nm, and (b) 3 nm BFO. The current measured at 100 mV is measured as a function of time and normalized by its value immediately after applying $V_{write}$ ($t = 0$s). Cian curves are fits of the relaxation of the OFF state using a stretched exponential function $I/I(t = 0s) = e^{-(t/\tau)^\beta}$. Both $\tau$ and $\beta$ fitting parameters are set free being $\tau \sim 10^8$ s and $10^{11}$s, and $\beta \sim 0.19$ and 0.10 for the 0nm and 3nm respectively.</figcaption></figure>